Local illumination compensation (lic) for virtual pipeline data units (vpdus)

ABSTRACT

Techniques are described herein for processing video data. For instance, a current block of a picture of the video data can be obtained, and it can be determined that the current block includes more than one virtual pipeline data unit (VPDU). Current neighbor samples for the current block, reference neighbor samples for the current block, and additional neighbor samples for the current block can be obtained for illumination compensation. One or more illumination compensation parameters can be determined for the current block using the current neighbor samples, the reference neighbor samples, and the additional neighbor samples. The additional neighbor samples are used for determining the one or more illumination compensation parameters based on the current block covering more than one VPDU. Illumination compensation can be performed for the current block using the one or more illumination compensation parameters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/788,725, filed Jan. 4, 2019, which is hereby incorporated byreference, in its entirety and for all purposes.

FIELD

This application is related to video coding and compression. Morespecifically, this application relates to systems and methods ofperforming improved local illumination compensation.

BACKGROUND

Many devices and systems allow video data to be processed and output forconsumption. Digital video data includes large amounts of data to meetthe demands of consumers and video providers. For example, consumers ofvideo data desire video of the utmost quality, with high fidelity,resolutions, frame rates, and the like. As a result, the large amount ofvideo data that is required to meet these demands places a burden oncommunication networks and devices that process and store the videodata.

Various video coding techniques may be used to compress video data.Video coding is performed according to one or more video codingstandards. For example, video coding standards include high-efficiencyvideo coding (HEVC), advanced video coding (AVC), MPEG-2 Part 2 coding(MPEG stands for moving picture experts group), VP9, Alliance of OpenMedia (AOMedia) Video 1 (AV1), Essential Video Coding (EVC), or thelike. Video coding generally utilizes prediction methods (e.g.,inter-prediction, intra-prediction, or the like) that take advantage ofredundancy present in video images or sequences. An important goal ofvideo coding techniques is to compress video data into a form that usesa lower bit rate, while avoiding or minimizing degradations to videoquality. With ever-evolving video services becoming available, encodingtechniques with better coding efficiency are needed.

BRIEF SUMMARY

Illumination compensation can be used to efficiently compensatevariations in illumination between one or more pictures. Techniques aredescribed herein to provide more efficient and less complex techniquesfor performing illumination compensation when a virtual pipeline dataunit (VPDU) processing structure is used.

According to at least one example, a method of processing video data isprovided. The method can include obtaining a current block of a pictureof the video data, and determining the current block includes more thanone virtual pipeline data unit (VPDU). The method can further includeobtaining, for illumination compensation, current neighbor samples forthe current block. The current neighbor samples include samples from oneor more of a first row of samples from a first neighboring block of afirst VPDU included in the current block or a first column of samplesfrom a second neighboring block of the first VPDU. The method canfurther include obtaining, for illumination compensation, referenceneighbor samples for the current block. The reference neighbor samplesinclude samples from one or more of a first row of samples from a firstneighboring block of a reference block or a first column of samples froma second neighboring block of the reference block. The method canfurther include obtaining, for illumination compensation, additionalneighbor samples for the current block. The additional neighbor samplesinclude samples from one or more of a second row of samples from thefirst neighboring block of the first VPDU, a second column of samplesfrom the second neighboring block of the first VPDU, a second row ofsamples from the first neighboring block of the reference block, asecond column of samples from the second neighboring block of thereference block, or samples from a neighboring block of a second VPDUincluded in the current block. The method can further includedetermining one or more illumination compensation parameters for thecurrent block using the current neighbor samples, the reference neighborsamples, and the additional neighbor samples. The additional neighborsamples are used for determining the one or more illuminationcompensation parameters based on the current block covering more thanone VPDU. The method can further include performing illuminationcompensation for the current block of the picture using the one or moreillumination compensation parameters.

According to another example, an apparatus for processing video data isprovided. The apparatus can include at least one memory and one or moreprocessors implemented in circuitry. The one or more processors areconfigured to obtain a current block of a picture of the video data, andto determine the current block includes more than one virtual pipelinedata unit (VPDU). The one or more processors are configured to obtain,for illumination compensation, current neighbor samples for the currentblock. The current neighbor samples include samples from one or more ofa first row of samples from a first neighboring block of a first VPDUincluded in the current block or a first column of samples from a secondneighboring block of the first VPDU. The one or more processors areconfigured to obtain, for illumination compensation, reference neighborsamples for the current block. The reference neighbor samples includesamples from one or more of a first row of samples from a firstneighboring block of a reference block or a first column of samples froma second neighboring block of the reference block. The one or moreprocessors are configured to obtain, for illumination compensation,additional neighbor samples for the current block. The additionalneighbor samples include samples from one or more of a second row ofsamples from the first neighboring block of the first VPDU, a secondcolumn of samples from the second neighboring block of the first VPDU, asecond row of samples from the first neighboring block of the referenceblock, a second column of samples from the second neighboring block ofthe reference block, or samples from a neighboring block of a secondVPDU included in the current block. The one or more processors areconfigured to determine one or more illumination compensation parametersfor the current block using the current neighbor samples, the referenceneighbor samples, and the additional neighbor samples. The additionalneighbor samples are used for determining the one or more illuminationcompensation parameters based on the current block covering more thanone VPDU. The one or more processors are configured to performillumination compensation for the current block of the picture using theone or more illumination compensation parameters.

According to another example, a non-transitory computer-readable mediumfor coding video data is provided. The non-transitory computer-readablemedium can include instructions stored thereon that, when executed byone or more processors, cause the one or more processors to: obtain acurrent block of a picture of the video data; determine the currentblock includes more than one virtual pipeline data unit (VPDU); obtain,for illumination compensation, current neighbor samples for the currentblock, the current neighbor samples including samples from one or moreof a first row of samples from a first neighboring block of a first VPDUincluded in the current block or a first column of samples from a secondneighboring block of the first VPDU; obtain, for illuminationcompensation, reference neighbor samples for the current block, thereference neighbor samples including samples from one or more of a firstrow of samples from a first neighboring block of a reference block or afirst column of samples from a second neighboring block of the referenceblock; obtain, for illumination compensation, additional neighborsamples for the current block, the additional neighbor samples includingsamples from one or more of a second row of samples from the firstneighboring block of the first VPDU, a second column of samples from thesecond neighboring block of the first VPDU, a second row of samples fromthe first neighboring block of the reference block, a second column ofsamples from the second neighboring block of the reference block, orsamples from a neighboring block of a second VPDU included in thecurrent block; determine one or more illumination compensationparameters for the current block using the current neighbor samples, thereference neighbor samples, and the additional neighbor samples, theadditional neighbor samples being used for determining the one or moreillumination compensation parameters based on the current block coveringmore than one VPDU; and perform illumination compensation for thecurrent block of the picture using the one or more illuminationcompensation parameters.

According to another example, an apparatus comprising means for codingvideo data is provided. The apparatus can include means for obtaining acurrent block of a picture of the video data, and means for determiningthe current block includes more than one virtual pipeline data unit(VPDU). The apparatus can include means obtaining, for illuminationcompensation, current neighbor samples for the current block. Thecurrent neighbor samples include samples from one or more of a first rowof samples from a first neighboring block of a first VPDU included inthe current block or a first column of samples from a second neighboringblock of the first VPDU. The apparatus can include means obtaining, forillumination compensation, reference neighbor samples for the currentblock. The reference neighbor samples include samples from one or moreof a first row of samples from a first neighboring block of a referenceblock or a first column of samples from a second neighboring block ofthe reference block. The apparatus can include means obtaining, forillumination compensation, additional neighbor samples for the currentblock. The additional neighbor samples include samples from one or moreof a second row of samples from the first neighboring block of the firstVPDU, a second column of samples from the second neighboring block ofthe first VPDU, a second row of samples from the first neighboring blockof the reference block, a second column of samples from the secondneighboring block of the reference block, or samples from a neighboringblock of a second VPDU included in the current block. The apparatus caninclude means determining one or more illumination compensationparameters for the current block using the current neighbor samples, thereference neighbor samples, and the additional neighbor samples. Theadditional neighbor samples are used for determining the one or moreillumination compensation parameters based on the current block coveringmore than one VPDU. The apparatus can include means performingillumination compensation for the current block of the picture using theone or more illumination compensation parameters.

In some aspects, the methods, apparatuses, and computer-readable mediadescribed above can include: determining a size of a VPDU; determiningone or more of a width or a height of the current block; determining oneor more of the width or the height of the current block is larger thanthe size of the VPDU; and determining the current block includes morethan one VPDU based on determining one or more of the width or theheight of the current block is larger than the size of the VPDU.

In some aspects, the first neighboring block of the first VPDU includesa top neighboring block, the second neighboring block of the first VPDUincludes a left neighboring block, the first neighboring block of thereference block includes a top neighboring block, and the secondneighboring block of the reference block includes a left neighboringblock.

In some aspects, subsampling is not applied to samples from the firstneighboring block of the first VPDU, samples from the second neighboringblock of the first VPDU, samples from the first neighboring block of thereference block, and samples from the second neighboring block of thereference block when performing illumination compensation for thecurrent block.

In some aspects, the additional neighbor samples include samples fromthe second row of samples from the first neighboring block of the firstVPDU and samples from the second column of samples from the secondneighboring block of the first VPDU. In some cases, the second row ofsamples from the first neighboring block of the first VPDU includes atleast two rows of samples, and the second column of samples from thesecond neighboring block of the first VPDU includes at least two columnsof samples.

In some aspects, the additional neighbor samples include samples fromthe second row of samples from the first neighboring block of the firstVPDU, samples from second column of samples from the second neighboringblock of the first VPDU, samples from the second row of samples from thefirst neighboring block of the reference block, and samples from thesecond column of samples from the second neighboring block of thereference block. In some cases, the second row of samples from the firstneighboring block of the first VPDU includes at least two rows ofsamples, the second column of samples from the second neighboring blockof the first VPDU includes at least two columns of samples, the secondrow of samples from the first neighboring block of the reference blockincludes at least two rows of samples, and the second column of samplesfrom the second neighboring block of the reference block includes atleast two columns of samples.

In some aspects, the additional neighbor samples include the samplesfrom the neighboring block of the second VPDU included in the currentblock. In some cases, the additional neighbor samples include samplesfrom a neighboring block of a third VPDU included in the current block.In some cases, the samples from the neighboring block of the second VPDUinclude a row of samples from the neighboring block of the second VPDU,and the samples from the neighboring block of the third VPDU include acolumn of samples from the neighboring block of the third VPDU. In someexamples, the row of samples from the first neighboring block of thesecond VPDU includes at least two rows of samples, and the column ofsamples from the neighboring block of the third VPDU includes at leasttwo columns of samples.

In some aspects, the additional neighbor samples include the samplesfrom the neighboring block of the second VPDU, samples from the secondrow of samples from the first neighboring block of the reference block,and samples from the second column of samples from the secondneighboring block of the reference block. In some cases, the samplesfrom the neighboring block of the second VPDU include a row of samplesfrom the neighboring block of the second VPDU and a column of samplesfrom a neighboring block of a third VPDU.

In some aspects, the additional neighbor samples include one or more ofsamples to a right of a top neighboring row of the current block,samples below a left neighboring column of the current block, samples toa right of a top neighboring row of the reference block, or samplesbelow a left neighboring column of the reference block.

In some aspects, determining the one or more illumination compensationparameters for the current block includes minimizing a differencebetween one or more of the samples from the first row of samples fromthe first neighboring block of the first VPDU or the samples from thefirst column of samples from the second neighboring block of the firstVPDU and one or more of the samples from the first row of samples fromthe first neighboring block of the reference block or the samples fromthe first column of samples from the second neighboring block of thereference block.

In some aspects, the one or more illumination compensation parametersinclude at least one scaling factor and at least one offset.

In some aspects, the methods, apparatuses, and computer-readable mediadescribed above can include decoding the current block of video databased on performing the illumination compensation for the current block.In some cases, the methods, apparatuses, and computer-readable mediadescribed above can include: determining a residual value for thecurrent block; performing a prediction mode for the current block; andreconstructing at least one sample of the current block based on theillumination compensation performed for the current block, the residualvalue for the current block, and the prediction mode performed for thecurrent block.

In some examples, the methods, apparatuses, and computer-readable mediadescribed above can include generating an encoded video bitstream. Theencoded video bitstream can include at least a portion of the currentblock of video data.

In some examples, the methods, apparatuses, and computer-readable mediadescribed above can include signaling the encoded video bitstream.

In some examples, the methods, apparatuses, and computer-readable mediadescribed above can include signaling the one or more illuminationcompensation parameters in the encoded video bitstream.

In some aspects, the apparatuses described above can include a mobiledevice. In some examples, the apparatus can include a camera forcapturing one or more pictures. In some examples, the apparatus caninclude a display for displaying one or more pictures. For example, theapparatus can include a mobile device (or other device) with a camerafor capturing one or more pictures. In another example, the apparatuscan include a mobile device (or other device) with a display fordisplaying one or more pictures. In another example, the apparatus caninclude a mobile device (or other device) with a camera for capturingone or more pictures and a display for displaying the one or morepictures.

This summary is not intended to identify key or essential features ofthe claimed subject matter, nor is it intended to be used in isolationto determine the scope of the claimed subject matter. The subject mattershould be understood by reference to appropriate portions of the entirespecification of this patent, any or all drawings, and each claim.

The foregoing, together with other features and embodiments, will becomemore apparent upon referring to the following specification, claims, andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present application are described indetail below with reference to the following figures:

FIG. 1 is a block diagram illustrating an example of an encoding deviceand a decoding device, in accordance with some examples;

FIG. 2A is a conceptual diagram illustrating example spatial neighboringmotion vector candidates for a merge mode, in accordance with someexamples;

FIG. 2B is a conceptual diagram illustrating example spatial neighboringmotion vector candidates for an advanced motion vector prediction (AMVP)mode, in accordance with some examples;

FIG. 3A is a conceptual diagram illustrating an example temporal motionvector predictor (TMVP) candidate, in accordance with some examples;

FIG. 3B is a conceptual diagram illustrating an example of motion vectorscaling, in accordance with some examples;

FIG. 4A is a conceptual diagram illustrating an example of neighboringsamples of a current coding unit used for estimating illuminationcompensation (IC) parameters for the current coding unit, in accordancewith some examples;

FIG. 4B is a conceptual diagram illustrating an example of neighboringsamples of a reference block used for estimating IC parameters for acurrent coding unit, in accordance with some examples;

FIG. 5A is a conceptual diagram illustrating an example of neighboringsamples of a current coding unit used for derivation of illuminationcompensation (IC) parameters for the current coding unit, in accordancewith some examples;

FIG. 5B is a conceptual diagram illustrating an example of neighboringsamples of a reference block used for derivation of IC parameters for acurrent coding unit, in accordance with some examples;

FIG. 6 is a conceptual diagram illustrating an example of neighborreconstructed samples of a current block and neighbor samples of areference block used for uni-directional inter-prediction, in accordancewith some examples;

FIG. 7 is a conceptual diagram illustrating an example of neighborreconstructed samples of a current block and neighbor samples of tworeference blocks used for bi-directional inter-prediction, in accordancewith some examples;

FIG. 8 is a conceptual diagram illustrating an example of a VPDUcontaining a single block, in accordance with some examples;

FIG. 9 is a conceptual diagram illustrating an example of a VPDUcontaining four blocks, in accordance with some examples;

FIG. 10 is a conceptual diagram illustrating an example of current blockspanning multiple VPDUs, in accordance with some examples;

FIG. 11 is a conceptual diagram illustrating an example relationship ofthe neighboring samples when a block size is inside one virtual pipelinedata unit (VPDU), in accordance with some examples;

FIG. 12 is a conceptual diagram illustrating an example relationship ofthe neighboring samples when a block covers more than one VPDU, inaccordance with some examples;

FIG. 13 is a conceptual diagram illustrating a proposed localillumination compensation (LIC) method for a VPDU split process usingonly the top and left neighboring samples of a VPDU for both the currentblock and the reference block, in accordance with some examples;

FIG. 14 is a conceptual diagram illustrating an example of performingLIC using multiples lines and columns of samples around a VPDU and areference block of the VPDU, in accordance with some examples;

FIG. 15 is a conceptual diagram illustrating an example of performingLIC using multiple lines and columns of samples around the referenceblock of a VPDU and using top and left neighboring samples around thecurrent block, in accordance with some examples;

FIG. 16 is a conceptual diagram illustrating an example of performingLIC using additional samples in the motion compensation (MC) accessmemory of a VPDU, in accordance with some examples;

FIG. 17 is a conceptual diagram illustrating another example ofperforming LIC using additional samples in the MC access memory of aVPDU, in accordance with some examples;

FIG. 18 is a flowchart illustrating an example of a process ofprocessing video data, in accordance with some embodiments;

FIG. 19 is a block diagram illustrating an example video encodingdevice, in accordance with some examples; and

FIG. 20 is a block diagram illustrating an example video decodingdevice, in accordance with some examples.

DETAILED DESCRIPTION

Certain aspects and embodiments of this disclosure are provided below.Some of these aspects and embodiments may be applied independently andsome of them may be applied in combination as would be apparent to thoseof skill in the art. In the following description, for the purposes ofexplanation, specific details are set forth in order to provide athorough understanding of embodiments of the application. However, itwill be apparent that various embodiments may be practiced without thesespecific details. The figures and description are not intended to berestrictive.

The ensuing description provides exemplary embodiments only, and is notintended to limit the scope, applicability, or configuration of thedisclosure. Rather, the ensuing description of the exemplary embodimentswill provide those skilled in the art with an enabling description forimplementing an exemplary embodiment. It should be understood thatvarious changes may be made in the function and arrangement of elementswithout departing from the spirit and scope of the application as setforth in the appended claims.

Video coding devices implement video compression techniques to encodeand decode video data efficiently. Video compression techniques mayinclude applying different prediction modes, including spatialprediction (e.g., intra-frame prediction or intra-prediction), temporalprediction (e.g., inter-frame prediction or inter-prediction),inter-layer prediction (across different layers of video data, and/orother prediction techniques to reduce or remove redundancy inherent invideo sequences. A video encoder can partition each picture of anoriginal video sequence into rectangular regions referred to as videoblocks or coding units (described in greater detail below). These videoblocks may be encoded using a particular prediction mode.

Video blocks may be divided in one or more ways into one or more groupsof smaller blocks. Blocks can include coding tree blocks, predictionblocks, transform blocks, or other suitable blocks. References generallyto a “block,” unless otherwise specified, may refer to such video blocks(e.g., coding tree blocks, coding blocks, prediction blocks, transformblocks, or other appropriate blocks or sub-blocks, as would beunderstood by one of ordinary skill. Further, each of these blocks mayalso interchangeably be referred to herein as “units” (e.g., coding treeunit (CTU), coding unit, prediction unit (PU), transform unit (TU), orthe like). In some cases, a unit may indicate a coding logical unit thatis encoded in a bitstream, while a block may indicate a portion of videoframe buffer a process is target to.

For inter-prediction modes, a video encoder can search for a blocksimilar to the block being encoded in a frame (or picture) located inanother temporal location, referred to as a reference frame or areference picture. The video encoder may restrict the search to acertain spatial displacement from the block to be encoded. A best matchmay be located using a two-dimensional (2D) motion vector that includesa horizontal displacement component and a vertical displacementcomponent. For intra-prediction modes, a video encoder may form thepredicted block using spatial prediction techniques based on data frompreviously encoded neighboring blocks within the same picture.

The video encoder may determine a prediction error. For example, theprediction can be determined as the difference between the pixel valuesin the block being encoded and the predicted block. The prediction errorcan also be referred to as the residual. The video encoder may alsoapply a transform to the prediction error (e.g., a discrete cosinetransform (DCT) or other suitable transform) to generate transformcoefficients. After transformation, the video encoder may quantize thetransform coefficients. The quantized transform coefficients and motionvectors may be represented using syntax elements, and, along withcontrol information, form a coded representation of a video sequence. Insome instances, the video encoder may entropy code syntax elements,thereby further reducing the number of bits needed for theirrepresentation.

A video decoder may, using the syntax elements and control informationdiscussed above, construct predictive data (e.g., a predictive block)for decoding a current frame. For example, the video decoder may add thepredicted block and the compressed prediction error. The video decodermay determine the compressed prediction error by weighting the transformbasis functions using the quantized coefficients. The difference betweenthe reconstructed frame and the original frame is called reconstructionerror.

In some examples, one or more systems and methods of processing videodata are directed to deriving or estimating illumination compensation(IC) parameters in block based video coding. In some instances, a videoencoder and/or a video decoder can perform local illuminationcompensation (LIC) (or illumination compensation) to efficiently codevariations in illumination (e.g., brightness) between one or morepictures. The video encoder and/or the video decoder can determine oneor more IC parameters (e.g., an offset, one or more scaling factors, ashift number, or other suitable IC parameters) for the coding block orcoding unit being encoded or decoded. The IC parameters can bedetermined based on samples of multiple reference blocks, samples of oneor more neighboring blocks of the current block, and/or otherinformation. The video decoder can utilize the IC parameters and/orother data to construct predictive data for decoding the current block.

FIG. 1 is a block diagram illustrating an example of a system 100including an encoding device 104 and a decoding device 112. The encodingdevice 104 may be part of a source device, and the decoding device 112may be part of a receiving device. The source device and/or thereceiving device may include an electronic device, such as a mobile orstationary telephone handset (e.g., smartphone, cellular telephone, orthe like), a desktop computer, a laptop or notebook computer, a tabletcomputer, a set-top box, a television, a camera, a display device, adigital media player, a video gaming console, a video streaming device,an Internet Protocol (IP) camera, or any other suitable electronicdevice. In some examples, the source device and the receiving device mayinclude one or more wireless transceivers for wireless communications.The coding techniques described herein are applicable to video coding invarious multimedia applications, including streaming video transmissions(e.g., over the Internet), television broadcasts or transmissions,encoding of digital video for storage on a data storage medium, decodingof digital video stored on a data storage medium, or other applications.In some examples, system 100 can support one-way or two-way videotransmission to support applications such as video conferencing, videostreaming, video playback, video broadcasting, gaming, and/or videotelephony.

The encoding device 104 (or encoder) can be used to encode video datausing a video coding standard or protocol to generate an encoded videobitstream. Examples of video coding standards include ITU-T H.261.ISO/IEC MPEG-1 Visual, ITU-T H.262 or ISO/IEC MPEG-2 Visual, ITU-TH.263, ISO/IEC MPEG-4 Visual. ITU-T H.264 (also known as ISO/IEC MPEG-4AVC), including its Scalable Video Coding (SVC) and Multiview VideoCoding (MVC) extensions, and High Efficiency Video Coding (HEVC) orITU-T H.265. Various extensions to HEVC deal with multi-layer videocoding exist, including the range and screen content coding extensions,3D video coding (3D-HEVC) and multiview extensions (MV-HEVC) andscalable extension (SHVC). The HEVC and its extensions have beendeveloped by the Joint Collaboration Team on Video Coding (JCT-VC) aswell as Joint Collaboration Team on 3D Video Coding ExtensionDevelopment (JCT-3V) of ITU-T Video Coding Experts Group (VCEG) andISO/IEC Motion Picture Experts Group (MPEG).

MPEG and ITU-T VCEG have also formed a joint exploration video team(JVET) to explore new coding tools for the next generation of videocoding standard, named Versatile Video Coding (VVC). The referencesoftware is called VVC Test Model (VTM) (or JEM (joint explorationmodel)). An objective of VVC is to provide a significant improvement incompression performance over the existing HEVC standard, aiding indeployment of higher-quality video services and emerging applications(e.g., such as 360° omnidirectional immersive multimedia,high-dynamic-range (HDR) video, among others). VP9, Alliance of OpenMedia (AOMedia) Video 1 (AV1), and Essential Video Coding (EVC) areother video coding standards for which the techniques described hereincan be applied.

The techniques described herein can be applied to any of the existingvideo codecs (e.g., High Efficiency Video Coding (HEVC), Advanced VideoCoding (AVC), or other suitable existing video codec), and/or can be anefficient coding tool for any video coding standards being developedand/or future video coding standards, such as, for example, VVC and/orother video coding standard in development or to be developed. Forexample, examples described herein can be performed using video codecssuch as VVC, HEVC, AVC, and/or extensions thereof. However, thetechniques and systems described herein may also be applicable to othercoding standards, such as MPEG, JPEG (or other coding standard for stillimages), VP9, AV1, extensions thereof, or other suitable codingstandards already available or not yet available or developed.Accordingly, while the techniques and systems described herein may bedescribed with reference to a particular video coding standard, one ofordinary skill in the art will appreciate that the description shouldnot be interpreted to apply only to that particular standard.

Referring to FIG. 1, a video source 102 may provide the video data tothe encoding device 104. The video source 102 may be part of the sourcedevice, or may be part of a device other than the source device. Thevideo source 102 may include a video capture device (e.g., a videocamera, a camera phone, a video phone, or the like), a video archivecontaining stored video, a video server or content provider providingvideo data, a video feed interface receiving video from a video serveror content provider, a computer graphics system for generating computergraphics video data, a combination of such sources, or any othersuitable video source.

The video data from the video source 102 may include one or more inputpictures or frames. A picture or frame is a still image that, in somecases, is part of a video. In some examples, data from the video source102 can be a still image that is not a part of a video. In HEVC, VVC,and other video coding specifications, a video sequence can include aseries of pictures. A picture may include three sample arrays, denotedS_(L), S_(Cb), and S_(Cr). S_(L) is a two-dimensional array of lumasamples, S_(Cb) is a two-dimensional array of Cb chrominance samples,and S_(Cr) is a two-dimensional array of Cr chrominance samples.Chrominance samples may also be referred to herein as “chroma” samples.A pixel can refer to all three components (luma and chroma samples) fora given location in an array of a picture. In other instances, a picturemay be monochrome and may only include an array of luma samples, inwhich case the terms pixel and sample can be used interchangeably. Withrespect to example techniques described herein that refer to individualsamples for illustrative purposes, the same techniques can be applied topixels (e.g., all three sample components for a given location in anarray of a picture). With respect to example techniques described hereinthat refer to pixels (e.g., all three sample components for a givenlocation in an array of a picture) for illustrative purposes, the sametechniques can be applied to individual samples.

The encoder engine 106 (or encoder) of the encoding device 104 encodesthe video data to generate an encoded video bitstream. In some examples,an encoded video bitstream (or “video bitstream” or “bitstream”) is aseries of one or more coded video sequences. A coded video sequence(CVS) includes a series of access units (AUs) starting with an AU thathas a random access point picture in the base layer and with certainproperties up to and not including a next AU that has a random accesspoint picture in the base layer and with certain properties. Forexample, the certain properties of a random access point picture thatstarts a CVS may include a RASL flag (e.g., NoRaslOutputFlag) equalto 1. Otherwise, a random access point picture (with RASL flag equal to0) does not start a CVS. An access unit (AU) includes one or more codedpictures and control information corresponding to the coded picturesthat share the same output time. Coded slices of pictures areencapsulated in the bitstream level into data units called networkabstraction layer (NAL) units. For example, an HEVC video bitstream mayinclude one or more CVSs including NAL units. Each of the NAL units hasa NAL unit header. In one example, the header is one-byte for H.264/AVC(except for multi-layer extensions) and two-byte for HEVC. The syntaxelements in the NAL unit header take the designated bits and thereforeare visible to all kinds of systems and transport layers, such asTransport Stream, Real-time Transport (RTP) Protocol, File Format, amongothers.

Two classes of NAL units exist in the HEVC standard, including videocoding layer (VCL) NAL units and non-VCL NAL units. A VCL NAL unitincludes one slice or slice segment (described below) of coded picturedata, and a non-VCL NAL unit includes control information that relatesto one or more coded pictures. In some cases, a NAL unit can be referredto as a packet. An HEVC AU includes VCL NAL units containing codedpicture data and non-VCL NAL units (if any) corresponding to the codedpicture data.

NAL units may contain a sequence of bits forming a coded representationof the video data (e.g., an encoded video bitstream, a CVS of abitstream, or the like), such as coded representations of pictures in avideo. The encoder engine 106 generates coded representations ofpictures by partitioning each picture into multiple slices. A slice isindependent of other slices so that information in the slice is codedwithout dependency on data from other slices within the same picture. Aslice includes one or more slice segments including an independent slicesegment and, if present, one or more dependent slice segments thatdepend on previous slice segments.

In HEVC, the slices are then partitioned into coding tree blocks (CTBs)of luma samples and chroma samples. A CTB of luma samples and one ormore CTBs of chroma samples, along with syntax for the samples, arereferred to as a coding tree unit (CTU). A CTU may also be referred toas a “tree block” or a “largest coding unit” (LCU). A CTU is the basicprocessing unit for HEVC encoding. A CTU can be split into multiplecoding units (CUs) of varying sizes. A CU contains luma and chromasample arrays that are referred to as coding blocks (CBs).

The luma and chroma CBs can be further split into prediction blocks(PBs). A PB is a block of samples of the luma component or a chromacomponent that uses the same motion parameters for inter-prediction orintra-block copy (IBC) prediction (when available or enabled for use).The luma PB and one or more chroma PBs, together with associated syntax,form a prediction unit (PU). For inter-prediction, a set of motionparameters (e.g., one or more motion vectors, reference indices, or thelike) is signaled in the bitstream for each PU and is used forinter-prediction of the luma PB and the one or more chroma PBs. Themotion parameters can also be referred to as motion information. A CBcan also be partitioned into one or more transform blocks (TBs). A TBrepresents a square block of samples of a color component on which aresidual transform (e.g., the same two-dimensional transform in somecases) is applied for coding a prediction residual signal. A transformunit (TU) represents the TBs of luma and chroma samples, andcorresponding syntax elements. Transform coding is described in moredetail below.

A size of a CU corresponds to a size of the coding mode and may besquare in shape. For example, a size of a CU may be 8×8 samples, 16×16samples, 32×32 samples, 64×64 samples, or any other appropriate size upto the size of the corresponding CTU. The phrase “N×N” is used herein torefer to pixel dimensions of a video block in terms of vertical andhorizontal dimensions (e.g., 8 pixels×8 pixels). The pixels in a blockmay be arranged in rows and columns. In some embodiments, blocks may nothave the same number of pixels in a horizontal direction as in avertical direction. Syntax data associated with a CU may describe, forexample, partitioning of the CU into one or more PUs. Partitioning modesmay differ between whether the CU is intra-prediction mode encoded orinter-prediction mode encoded. PUs may be partitioned to be non-squarein shape. Syntax data associated with a CU may also describe, forexample, partitioning of the CU into one or more TUs according to a CTU.A TU can be square or non-square in shape.

According to the HEVC standard, transformations may be performed usingtransform units (TUs). TUs may vary for different CUs. The TUs may besized based on the size of PUs within a given CU. The TUs may be thesame size or smaller than the PUs. In some examples, residual samplescorresponding to a CU may be subdivided into smaller units using aquadtree structure known as residual quad tree (RQT). Leaf nodes of theRQT may correspond to TUs. Pixel difference values associated with theTUs may be transformed to produce transform coefficients. The transformcoefficients may then be quantized by the encoder engine 106.

Once the pictures of the video data are partitioned into CUs, theencoder engine 106 predicts each PU using a prediction mode. Theprediction unit or prediction block is then subtracted from the originalvideo data to get residuals (described below). For each CU, a predictionmode may be signaled inside the bitstream using syntax data. Aprediction mode may include intra-prediction (or intra-pictureprediction) or inter-prediction (or inter-picture prediction).Intra-prediction utilizes the correlation between spatially neighboringsamples within a picture. For example, using intra-prediction, each PUis predicted from neighboring image data in the same picture using, forexample, DC prediction to find an average value for the PU, planarprediction to fit a planar surface to the PU, direction prediction toextrapolate from neighboring data, or any other suitable types ofprediction. Inter-prediction uses the temporal correlation betweenpictures in order to derive a motion-compensated prediction for a blockof image samples. For example, using inter-prediction, each PU ispredicted using motion compensation prediction from image data in one ormore reference pictures (before or after the current picture in outputorder). The decision whether to code a picture area using inter-pictureor intra-picture prediction may be made, for example, at the CU level.

The encoder engine 106 and decoder engine 116 (described in more detailbelow) may be configured to operate according to VVC. According to VVC,a video coder (such as encoder engine 106 and/or decoder engine 116)partitions a picture into a plurality of coding tree units (CTUs) (wherea CTB of luma samples and one or more CTBs of chroma samples, along withsyntax for the samples, are referred to as a CTU). The video coder canpartition a CTU according to a tree structure, such as a quadtree-binarytree (QTBT) structure or Multi-Type Tree (MTT) structure. The QTBTstructure removes the concepts of multiple partition types, such as theseparation between CUs, PUs, and TUs of HEVC. A QTBT structure includestwo levels, including a first level partitioned according to quadtreepartitioning, and a second level partitioned according to binary treepartitioning. A root node of the QTBT structure corresponds to a CTU.Leaf nodes of the binary trees correspond to coding units (CUs).

In an MTT partitioning structure, blocks may be partitioned using aquadtree partition, a binary tree partition, and one or more types oftriple tree partitions. A triple tree partition is a partition where ablock is split into three sub-blocks. In some examples, a triple treepartition divides a block into three sub-blocks without dividing theoriginal block through the center. The partitioning types in MTT (e.g.,quadtree, binary tree, and tripe tree) may be symmetrical orasymmetrical.

In some examples, the video coder can use a single QTBT or MTT structureto represent each of the luminance and chrominance components, while inother examples, the video coder can use two or more QTBT or MTTstructures, such as one QTBT or MTT structure for the luminancecomponent and another QTBT or MTT structure for both chrominancecomponents (or two QTBT and/or MTT structures for respective chrominancecomponents).

The video coder can be configured to use quadtree partitioning per HEVC,QTBT partitioning, MTT partitioning, or other partitioning structures.For illustrative purposes, the description herein may refer to QTBTpartitioning. However, it should be understood that the techniques ofthis disclosure may also be applied to video coders configured to usequadtree partitioning, or other types of partitioning as well.

In some examples, the one or more slices of a picture are assigned aslice type. Slice types include an I slice, a P slice, and a B slice. AnI slice (intra-frames, independently decodable) is a slice of a picturethat is only coded by intra-prediction, and therefore is independentlydecodable since the I slice requires only the data within the frame topredict any prediction unit or prediction block of the slice. A P slice(uni-directional predicted frames) is a slice of a picture that may becoded with intra-prediction and with uni-directional inter-prediction.Each prediction unit or prediction block within a P slice is eithercoded with intra-prediction or inter-prediction. When theinter-prediction applies, the prediction unit or prediction block isonly predicted by one reference picture, and therefore reference samplesare only from one reference region of one frame. A B slice(bi-directional predictive frames) is a slice of a picture that may becoded with intra-prediction and with inter-prediction (e.g., eitherbi-prediction or uni-prediction). A prediction unit or prediction blockof a B slice may be bi-directionally predicted from two referencepictures, where each picture contributes one reference region and samplesets of the two reference regions are weighted (e.g., with equal weightsor with different weights) to produce the prediction signal of thehi-directional predicted block. As explained above, slices of onepicture are independently coded. In some cases, a picture can be codedas just one slice.

As noted above, intra-picture prediction of a picture utilizes thecorrelation between spatially neighboring samples within the picture.There is a plurality of intra-prediction modes (also referred to as“intra modes”). In some examples, the intra prediction of a luma blockincludes 35 modes, including the Planar mode, DC mode, and 33 angularmodes (e.g., diagonal intra prediction modes and angular modes adjacentto the diagonal intra prediction modes). The 35 modes of the intraprediction are indexed as shown in Table 1 below. In other examples,more intra modes may be defined including prediction angles that may notalready be represented by the 33 angular modes. In other examples, theprediction angles associated with the angular modes may be differentfrom those used in HEVC.

TABLE 1 Specification of intra prediction mode and associated namesIntra-prediction mode Associated name 0 INTRA_PLANAR 1 INTRA_DC 2..34INTRA_ANGULAR2..INTRA_ANGULAR34

Inter-picture prediction uses the temporal correlation between picturesin order to derive a motion-compensated prediction for a block of imagesamples. Using a translational motion model, the position of a block ina previously decoded picture (a reference picture) is indicated by amotion vector (Δx, Δy), with Δx specifying the horizontal displacementand Δy specifying the vertical displacement of the reference blockrelative to the position of the current block. In some cases, a motionvector (Δx, Δy) can be in integer sample accuracy (also referred to asinteger accuracy), in which case the motion vector points to theinteger-pel grid (or integer-pixel sampling grid) of the referenceframe. In some cases, a motion vector (Δx, Δy) can be of fractionalsample accuracy (also referred to as fractional-pel accuracy ornon-integer accuracy) to more accurately capture the movement of theunderlying object, without being restricted to the integer-pel grid ofthe reference frame. Accuracy of motion vectors may be expressed by thequantization level of the motion vectors. For example, the quantizationlevel may be integer accuracy (e.g., 1-pixel) or fractional-pel accuracy(e.g., ¼-pixel, ½-pixel, or other sub-pixel value). Interpolation isapplied on reference pictures to derive the prediction signal when thecorresponding motion vector has fractional sample accuracy. For example,samples available at integer positions can be filtered (e.g., using oneor more interpolation filters) to estimate values at fractionalpositions. The previously decoded reference picture is indicated by areference index (refIdx) to a reference picture list. The motion vectorsand reference indices can be referred to as motion parameters. Two kindsof inter-picture prediction can be performed, including uni-predictionand bi-prediction.

With inter-prediction using bi-prediction, two sets of motion parameters(Δx₀, y₀, refIdx₀ and Δx₁, y₁, refIdx₁) are used to generate two motioncompensated predictions (from the same reference picture or possiblyfrom different reference pictures). For example, with bi-prediction,each prediction block uses two motion compensated prediction signals,and generates B prediction units. The two motion compensated predictionsare then combined to get the final motion compensated prediction. Forexample, the two motion compensated predictions can be combined byaveraging. In another example, weighted prediction can be used, in whichcase different weights can be applied to each motion compensatedprediction. The reference pictures that can be used in bi-prediction arestored in two separate lists, denoted as list 0 and list 1. Motionparameters can be derived at the encoder using a motion estimationprocess.

With inter-prediction using uni-prediction, one set of motion parameters(Δx₀, y₀, refIdx₀) is used to generate a motion compensated predictionfrom a reference picture. For example, with uni-prediction, eachprediction block uses at most one motion compensated prediction signal,and generates P prediction units.

A PU may include the data (e.g., motion parameters or other suitabledata) related to the prediction process. For example, when the PU isencoded using intra-prediction, the PU may include data describing anintra-prediction mode for the PU. As another example, when the PU isencoded using inter-prediction, the PU may include data defining amotion vector for the PU. The data defining the motion vector for a PUmay describe, for example, a horizontal component of the motion vector(Δx), a vertical component of the motion vector (Δy), a resolution forthe motion vector (e.g., integer precision, one-quarter pixel precisionor one-eighth pixel precision), a reference picture to which the motionvector points, a reference index, a reference picture list (e.g., List0, List 1, or List C) for the motion vector, or any combination thereof.

After performing prediction using intra- and/or inter-prediction, theencoding device 104 can perform transformation and quantization. Forexample, following prediction, the encoder engine 106 may calculateresidual values corresponding to the PU. Residual values may comprisepixel difference values between the current block of pixels being coded(the PU) and the prediction block used to predict the current block(e.g., the predicted version of the current block). For example, aftergenerating a prediction block (e.g., issuing inter-prediction orintra-prediction), the encoder engine 106 can generate a residual blockby subtracting the prediction block produced by a prediction unit fromthe current block. The residual block includes a set of pixel differencevalues that quantify differences between pixel values of the currentblock and pixel values of the prediction block. In some examples, theresidual block may be represented in a two-dimensional block format(e.g., a two-dimensional matrix or array of pixel values). In suchexamples, the residual block is a two-dimensional representation of thepixel values.

Any residual data that may be remaining after prediction is performed istransformed using a block transform, which may be based on discretecosine transform, discrete sine transform, an integer transform, awavelet transform, other suitable transform function, or any combinationthereof. In some cases, one or more block transforms (e.g., sizes 32×32,16×16, 8×8, 4×4, or other suitable size) may be applied to residual datain each CU. In some embodiments, a TU may be used for the transform andquantization processes implemented by the encoder engine 106. A given CUhaving one or more PUs may also include one or more TUs. As described infurther detail below, the residual values may be transformed intotransform coefficients using the block transforms, and then may bequantized and scanned using TUs to produce serialized transformcoefficients for entropy coding.

In some embodiments following intra-predictive or inter-predictivecoding using PUs of a CU, the encoder engine 106 may calculate residualdata for the TUs of the CU. The PUs may comprise pixel data in thespatial domain (or pixel domain). The TUs may comprise coefficients inthe transform domain following application of a block transform. Aspreviously noted, the residual data may correspond to pixel differencevalues between pixels of the unencoded picture and prediction valuescorresponding to the PUs. Encoder engine 106 may form the TUs includingthe residual data for the CU, and may then transform the TUs to producetransform coefficients for the CU.

The encoder engine 106 may perform quantization of the transformcoefficients. Quantization provides further compression by quantizingthe transform coefficients to reduce the amount of data used torepresent the coefficients. For example, quantization may reduce the bitdepth associated with some or all of the coefficients. In one example, acoefficient with an n-bit value may be rounded down to an m-bit valueduring quantization, with n being greater than m.

Once quantization is performed, the coded video bitstream includesquantized transform coefficients, prediction information (e.g.,prediction modes, motion vectors, block vectors, or the like),partitioning information, and any other suitable data, such as othersyntax data. The different elements of the coded video bitstream maythen be entropy encoded by the encoder engine 106. In some examples, theencoder engine 106 may utilize a predefined scan order to scan thequantized transform coefficients to produce a serialized vector that canbe entropy encoded. In some examples, encoder engine 106 may perform anadaptive scan. After scanning the quantized transform coefficients toform a vector (e.g., a one-dimensional vector), the encoder engine 106may entropy encode the vector. For example, the encoder engine 106 mayuse context adaptive variable length coding, context adaptive binaryarithmetic coding, syntax-based context-adaptive binary arithmeticcoding, probability interval partitioning entropy coding, or anothersuitable entropy encoding technique.

As previously described, an HEVC bitstream includes a group of NALunits, including VCL NAL units and non-VCL NAL units. VCL NAL unitsinclude coded picture data forming a coded video bitstream. For example,a sequence of bits forming the coded video bitstream is present in VCLNAL units. Non-VCL NAL units may contain parameter sets with high-levelinformation relating to the encoded video bitstream, in addition toother information. For example, a parameter set may include a videoparameter set (VPS), a sequence parameter set (SPS), and a pictureparameter set (PPS). Examples of goals of the parameter sets include bitrate efficiency, error resiliency, and providing systems layerinterfaces. Each slice references a single active PPS. SPS, and VPS toaccess information that the decoding device 112 may use for decoding theslice. An identifier (ID) may be coded for each parameter set, includinga VPS ID, an SPS ID, and a PPS ID. An SPS includes an SPS ID and a VPSID. A PPS includes a PPS ID and an SPS ID. Each slice header includes aPPS ID. Using the IDs, active parameter sets can be identified for agiven slice.

A PPS includes information that applies to all slices in a givenpicture. Because of this, all slices in a picture refer to the same PPS.Slices in different pictures may also refer to the same PPS. An SPSincludes information that applies to all pictures in a same coded videosequence (CVS) or bitstream. As previously described, a coded videosequence is a series of access units (AUs) that starts with a randomaccess point picture (e.g., an instantaneous decode reference (IDR)picture or broken link access (BLA) picture, or other appropriate randomaccess point picture) in the base layer and with certain properties(described above) up to and not including a next AU that has a randomaccess point picture in the base layer and with certain properties (orthe end of the bitstream). The information in an SPS may not change frompicture to picture within a coded video sequence. Pictures in a codedvideo sequence may use the same SPS. The VPS includes information thatapplies to all layers within a coded video sequence or bitstream. TheVPS includes a syntax structure with syntax elements that apply toentire coded video sequences. In some embodiments, the VPS, SPS, or PPSmay be transmitted in-band with the encoded bitstream. In someembodiments, the VPS, SPS, or PPS may be transmitted out-of-band in aseparate transmission than the NAL units containing coded video data.

A video bitstream can also include Supplemental Enhancement Information(SEI) messages. For example, an SEI NAL unit can be part of the videobitstream. In some cases, an SEI message can contain information that isnot needed by the decoding process. For example, the information in anSE message may not be essential for the decoder to decode the videopictures of the bitstream, but the decoder can be use the information toimprove the display or processing of the pictures (e.g., the decodedoutput). The information in an SEI message can be embedded metadata. Inone illustrative example, the information in an SEI message could beused by decoder-side entities to improve the viewability of the content.In some instances, certain application standards may mandate thepresence of such SEI messages in the bitstream so that the improvementin quality can be brought to all devices that conform to the applicationstandard (e.g., the carriage of the frame-packing SEI message forframe-compatible plano-stereoscopic 3DTV video format, where the SEImessage is carried for every frame of the video, handling of a recoverypoint SEI message, use of pan-scan scan rectangle SEI message in DVB, inaddition to many other examples).

The output 110 of the encoding device 104 may send the NAL units makingup the encoded video bitstream data over the communications link 120 tothe decoding device 112 of the receiving device. The input 114 of thedecoding device 112 may receive the NAL units. The communications link120 may include a channel provided by a wireless network, a wirednetwork, or a combination of a wired and wireless network. A wirelessnetwork may include any wireless interface or combination of wirelessinterfaces and may include any suitable wireless network (e.g., theInternet or other wide area network, a packet-based network. WiFi™,radio frequency (RF), UWB, WiFi-Direct, cellular, Long-Term Evolution(LTE), WiMax™, or the like). A wired network may include any wiredinterface (e.g., fiber, ethernet, powerline ethernet, ethernet overcoaxial cable, digital signal line (DSL), or the like). The wired and/orwireless networks may be implemented using various equipment, such asbase stations, routers, access points, bridges, gateways, switches, orthe like. The encoded video bitstream data may be modulated according toa communication standard, such as a wireless communication protocol, andtransmitted to the receiving device.

In some examples, the encoding device 104 may store encoded videobitstream data in storage 108. The output 110 may retrieve the encodedvideo bitstream data from the encoder engine 106 or from the storage108. Storage 108 may include any of a variety of distributed or locallyaccessed data storage media. For example, the storage 108 may include ahard drive, a storage disc, flash memory, volatile or non-volatilememory, or any other suitable digital storage media for storing encodedvideo data. The storage 108 can also include a decoded picture buffer(DPB) for storing reference pictures for use in inter-prediction. In afurther example, the storage 108 can correspond to a file server oranother intermediate storage device that may store the encoded videogenerated by the source device. In such cases, the receiving deviceincluding the decoding device 112 can access stored video data from thestorage device via streaming or download. The file server may be anytype of server capable of storing encoded video data and transmittingthat encoded video data to the receiving device. Example file serversinclude a web server (e.g., for a website), an FTP server, networkattached storage (NAS) devices, or a local disk drive. The receivingdevice may access the encoded video data through any standard dataconnection, including an Internet connection. This may include awireless channel (e.g., a Wi-Fi connection), a wired connection (e.g.,DSL, cable modem, etc.), or a combination of both that is suitable foraccessing encoded video data stored on a file server. The transmissionof encoded video data from the storage 108 may be a streamingtransmission, a download transmission, or a combination thereof.

The input 114 of the decoding device 112 receives the encoded videobitstream data and may provide the video bitstream data to the decoderengine 116, or to storage 118 for later use by the decoder engine 116.For example, the storage 118 can include a DPB for storing referencepictures for use in inter-prediction. The receiving device including thedecoding device 112 can receive the encoded video data to be decoded viathe storage 108. The encoded video data may be modulated according to acommunication standard, such as a wireless communication protocol, andtransmitted to the receiving device. The communication medium fortransmitted the encoded video data can comprise any wireless or wiredcommunication medium, such as a radio frequency (RF) spectrum or one ormore physical transmission lines. The communication medium may form partof a packet-based network, such as a local area network, a wide-areanetwork, or a global network such as the Internet. The communicationmedium may include routers, switches, base stations, or any otherequipment that may be useful to facilitate communication from the sourcedevice to the receiving device.

The decoder engine 116 may decode the encoded video bitstream data byentropy decoding (e.g., using an entropy decoder) and extracting theelements of one or more coded video sequences making up the encodedvideo data. The decoder engine 116 may then rescale and perform aninverse transform on the encoded video bitstream data. Residual data isthen passed to a prediction stage of the decoder engine 116. The decoderengine 116 then predicts a block of pixels (e.g., a PU). In someexamples, the prediction is added to the output of the inverse transform(the residual data).

The decoding device 112 may output the decoded video to a videodestination device 122, which may include a display or other outputdevice for displaying the decoded video data to a consumer of thecontent. In some aspects, the video destination device 122 may be partof the receiving device that includes the decoding device 112. In someaspects, the video destination device 122 may be part of a separatedevice other than the receiving device.

In some embodiments, the video encoding device 104 and/or the videodecoding device 112 may be integrated with an audio encoding device andaudio decoding device, respectively. The video encoding device 104and/or the video decoding device 112 may also include other hardware orsoftware that is necessary to implement the coding techniques describedabove, such as one or more microprocessors, digital signal processors(DSPs), application specific integrated circuits (ASICs), fieldprogrammable gate arrays (FPGAs), discrete logic, software, hardware,firmware or any combinations thereof. The video encoding device 104 andthe video decoding device 112 may be integrated as part of a combinedencoder/decoder (codec) in a respective device. An example of specificdetails of the encoding device 104 is described below with reference toFIG. 11. An example of specific details of the decoding device 112 isdescribed below with reference to FIG. 12.

The example system shown in FIG. 1 is one illustrative example that canbe used herein. Techniques for processing video data using thetechniques described herein can be performed by any digital videoencoding and/or decoding device. Although generally the techniques ofthis disclosure are performed by a video encoding device or a videodecoding device, the techniques may also be performed by a combinedvideo encoder-decoder, typically referred to as a “CODEC.” Moreover, thetechniques of this disclosure may also be performed by a videopreprocessor. The source device and the receiving device are merelyexamples of such coding devices in which the source device generatescoded video data for transmission to the receiving device. In someexamples, the source and receiving devices may operate in asubstantially symmetrical manner such that each of the devices includevideo encoding and decoding components. Hence, example systems maysupport one-way or two-way video transmission between video devices,e.g., for video streaming, video playback, video broadcasting, or videotelephony.

Extensions to the HEVC standard include the Multiview Video Codingextension, referred to as MV-HEVC, and the Scalable Video Codingextension, referred to as SHVC. The MV-HEVC and SHVC extensions sharethe concept of layered coding, with different layers being included inthe encoded video bitstream. Each layer in a coded video sequence isaddressed by a unique layer identifier (ID). A layer ID may be presentin a header of a NAL unit to identify a layer with which the NAL unit isassociated. In MV-HEVC, different layers can represent different viewsof the same scene in the video bitstream. In SHVC, different scalablelayers are provided that represent the video bitstream in differentspatial resolutions (or picture resolution) or in differentreconstruction fidelities. The scalable layers may include a base layer(with layer ID=0) and one or more enhancement layers (with layer IDs=1,2 . . . . n). The base layer may conform to a profile of the firstversion of HEVC, and represents the lowest available layer in abitstream. The enhancement layers have increased spatial resolution,temporal resolution or frame rate, and/or reconstruction fidelity (orquality) as compared to the base layer. The enhancement layers arehierarchically organized and may (or may not) depend on lower layers. Insome examples, the different layers may be coded using a single standardcodec (e.g., all layers are encoded using HEVC, SHVC, or other codingstandard). In some examples, different layers may be coded using amulti-standard codec. For example, a base layer may be coded using AVC,while one or more enhancement layers may be coded using SHVC and/orMV-HEVC extensions to the HEVC standard.

In general, a layer includes a set of VCL NAL units and a correspondingset of non-VCL NAL units. The NAL units are assigned a particular layerID value. Layers can be hierarchical in the sense that a layer maydepend on a lower layer. A layer set refers to a set of layersrepresented within a bitstream that are self-contained, meaning that thelayers within a layer set can depend on other layers in the layer set inthe decoding process, but do not depend on any other layers fordecoding. Accordingly, the layers in a layer set can form an independentbitstream that can represent video content. The set of layers in a layerset may be obtained from another bitstream by operation of asub-bitstream extraction process. A layer set may correspond to the setof layers that is to be decoded when a decoder wants to operateaccording to certain parameters.

As described above, for each block, a set of motion information (alsoreferred to herein as motion parameters) can be available. A set ofmotion information contains motion information for forward and backwardprediction directions. The forward and backward prediction directionsare two prediction directions of a bi-directional prediction mode, inwhich case the terms “forward” and “backward” do not necessarily have ageometrical meaning. Instead. “forward” and “backward” correspond toreference picture list 0 (RefPicList0 or L0) and reference picture list1 (RefPicList1 or L1) of a current picture. In some examples, when onlyone reference picture list is available for a picture or slice, onlyRefPicList0 is available and the motion information of each block of aslice is always forward.

In some cases, a motion vector together with its reference index is usedin coding processes (e.g., motion compensation). Such a motion vectorwith the associated reference index is denoted as a uni-predictive setof motion information. For each prediction direction, the motioninformation can contain a reference index and a motion vector. In somecases, for simplicity, a motion vector itself may be referred in a waythat it is assumed that it has an associated reference index. Areference index is used to identify a reference picture in the currentreference picture list (RefPicList0 or RefPicList1). A motion vector hasa horizontal and a vertical component that provide an offset from thecoordinate position in the current picture to the coordinates in thereference picture identified by the reference index. For example, areference index can indicate a particular reference picture that shouldbe used for a block in a current picture, and the motion vector canindicate where in the reference picture the best-matched block (theblock that best matches the current block) is in the reference picture.

A picture order count (POC) can be used in video coding standards toidentify a display order of a picture. Although there are cases forwhich two pictures within one coded video sequence may have the same POCvalue, it typically does not happen within a coded video sequence. Whenmultiple coded video sequences are present in a bitstream, pictures witha same value of POC may be closer to each other in terms of decodingorder. POC values of pictures can be used for reference picture listconstruction, derivation of reference picture set as in HEVC, and motionvector scaling.

In H.264/AVC, each inter macroblock (MB) may be partitioned in fourdifferent ways, including: one 16×16 MB partition: two 16×8 MBpartitions: two 8×16 MB partitions; and four 8×8 MB partitions.Different MB partitions in one MB may have different reference indexvalues for each direction (RefPicList0 or RetPicList1). In some cases,when an MB is not partitioned into four 8×8 MB partitions, it can haveonly one motion vector for each MB partition in each direction. In somecases, when an MB is partitioned into four 8×8 MB partitions, each 8×8MB partition can be further partitioned into sub-blocks, in which caseeach sub-block can have a different motion vector in each direction. Insome examples, there are four different ways to get sub-blocks from an8×8 MB partition, including: one 8×8 sub-block; two 8×4 sub-blocks; two4×8 sub-blocks; and four 4×4 sub-blocks. Each sub-block can have adifferent motion vector in each direction. Therefore, a motion vector ispresent in a level equal to higher than sub-block.

In AVC, a temporal direct mode can be enabled at either the MB level orthe MB partition level for skip and/or direct mode in B slices. For eachMB partition, the motion vectors of the block co-located with thecurrent MB partition in the RefPicList1[0] of the current block are usedto derive the motion vectors. Each motion vector in the co-located blockis scaled based on POC distances.

A spatial direct mode can also be performed in AVC. For example, in AVC,a direct mode can also predict motion information from the spatialneighbors.

As noted above, in HEVC, the largest coding unit in a slice is called acoding tree block (CTB). A CTB contains a quad-tree, the nodes of whichare coding units. The size of a CTB can range from 16×16 to 64×64 in theHEVC main profile. In some cases, 8×8 CTB sizes can be supported. Acoding unit (CU) could be the same size of a CTB and as small as 8×8. Insome cases, each coding unit is coded with one mode. When a CU isinter-coded, the CU may be further partitioned into 2 or 4 predictionunits (PUs), or may become just one PU when further partition does notapply. When two PUs are present in one CU, they can be half sizerectangles or two rectangles with or % size of the CU.

When the CU is inter-coded, one set of motion information is present foreach PU. In addition, each PU is coded with a unique inter-predictionmode to derive the set of motion information.

For motion prediction in HEVC, there are two inter-prediction modes,including merge mode and advanced motion vector prediction (AMVP) modefor a prediction unit (PU). Skip is considered as a special case ofmerge. In either AMVP or merge mode, a motion vector (MV) candidate listis maintained for multiple motion vector predictors. The motionvector(s), as well as reference indices in the merge mode, of thecurrent PU are generated by taking one candidate from the MV candidatelist. In some examples, as described below, one or more stored localillumination compensation (LIC) flags can be included along with storedmotion vectors in a MV candidate list.

In examples where a MV candidate list is used for motion prediction (andwhere applicable, illumination compensation) of a block, the MVcandidate list may be constructed by the encoding device and thedecoding device separately. For instance, the MV candidate list can begenerated by an encoding device when encoding a block, and can begenerated by a decoding device when decoding the block. Informationrelated to motion information candidates in the MV candidate list (e.g.information related to one or more motion vectors, information relatedto one or more LIC flags which can be stored in the MV candidate list insome cases, and/or other information), can be signaled between theencoding device and the decoding device. For example, in the merge mode,index values to the stored motion information candidates can be signaledfrom an encoding device to a decoding device (e.g., in a syntaxstructure, such as the picture parameter set (PPS), sequence parameterset (SPS), video parameter set (VPS), a slice header, a supplementalenhancement information (SEI) message sent in or separately from thevideo bitstream, and/or other signaling). The decoding device canconstruct a MV candidate list and use the signaled references or indexesto obtain one or more motion information candidates from the constructedMV candidate list to use for motion compensation prediction. Forexample, the decoding device 112 may construct a MV candidate list anduse a motion vector (and in some cases an LIC flag) from an indexedlocation for motion prediction of the block. In the case of AMVP mode,in addition to the references or indexes, differences or residual valuesmay also be signaled as deltas. For example, for the AMVP mode, thedecoding device can construct one or more MV candidate lists and applythe delta values to one or more motion information candidates obtainedusing the signaled index values in performing motion compensationprediction of the block.

In some examples, the MV candidate list contains up to five candidatesfor the merge mode and two candidates for the AMVP mode. In otherexamples, different numbers of candidates can be included in a MVcandidate list for merge mode and/or AMVP mode. A merge candidate maycontain a set of motion information. For example, a set of motioninformation can include motion vectors corresponding to both referencepicture lists (list 0 and list 1) and the reference indices. If a mergecandidate is identified by a merge index, the reference pictures areused for the prediction of the current blocks, as well as the associatedmotion vectors are determined. However, under AMVP mode, for eachpotential prediction direction from either list 0 or list 1, a referenceindex needs to be explicitly signaled, together with an MVP index to theMV candidate list since the AMVP candidate contains only a motionvector. In AMVP mode, the predicted motion vectors can be furtherrefined.

As can be seen above, a merge candidate corresponds to a full set ofmotion information, while an AMVP candidate contains just one motionvector for a specific prediction direction and reference index. Thecandidates for both modes are derived similarly from the same spatialand temporal neighboring blocks.

In some examples, merge mode allows an inter-predicted PU to inherit thesame motion vector or vectors, prediction direction, and referencepicture index or indices from an inter-predicted PU that includes amotion data position selected from a group of spatially neighboringmotion data positions and one of two temporally co-located motion datapositions. For AMVP mode, motion vector or vectors of a PU can bepredicatively coded relative to one or more motion vector predictors(MVPs) from an AMVP candidate list constructed by an encoder and/or adecoder. In some instances, for single direction inter-prediction of aPU, the encoder and/or decoder can generate a single AMVP candidatelist. In some instances, for bi-directional prediction of a PU, theencoder and/or decoder can generate two AMVP candidate lists, one usingmotion data of spatial and temporal neighboring PUs from the forwardprediction direction and one using motion data of spatial and temporalneighboring PUs from the backward prediction direction.

The candidates for both modes can be derived from spatial and/ortemporal neighboring blocks. For example, FIG. 2A and FIG. 2B includeconceptual diagrams illustrating spatial neighboring candidates in HEVC.FIG. 2A illustrates spatial neighboring motion vector (MV) candidatesfor merge mode. FIG. 2B illustrates spatial neighboring motion vector(MV) candidates for AMVP mode. Spatial MV candidates are derived fromthe neighboring blocks for a specific PU (PU0), although the methodsgenerating the candidates from the blocks differ for merge and AMVPmodes.

In merge mode, the encoder and/or decoder can form a merging candidatelist by considering merging candidates from various motion datapositions. For example, as shown in FIG. 2A, up to four spatial MVcandidates can be derived with respect spatially neighboring motion datapositions shown with numbers 0-4 in FIG. 2A. The MV candidates can beordered in the merging candidate list in the order shown by the numbers0-4. For example, the positions and order can include: left position(0), above position (1), above right position (2), below left position(3), and above left position (4).

In AVMP mode shown in FIG. 2B, the neighboring blocks are divided intotwo groups: left group including the blocks 0 and 1, and above groupincluding the blocks 2, 3, and 4. For each group, the potentialcandidate in a neighboring block referring to the same reference pictureas that indicated by the signaled reference index has the highestpriority to be chosen to form a final candidate of the group. It ispossible that all neighboring blocks do not contain a motion vectorpointing to the same reference picture. Therefore, if such a candidatecannot be found, the first available candidate will be scaled to formthe final candidate, thus the temporal distance differences can becompensated.

FIG. 3A and FIG. 3B include conceptual diagrams illustrating temporalmotion vector prediction in HEVC. A temporal motion vector predictor(TMVP) candidate, if enabled and available, is added into a MV candidatelist after spatial motion vector candidates. The process of motionvector derivation for a TMVP candidate is the same for both merge andAMVP modes. In some instances, however, the target reference index forthe TMVP candidate in the merge mode can be set to zero or can bederived from that of the neighboring blocks.

The primary block location for TMVP candidate derivation is the bottomright block outside of the collocated PU, as shown in FIG. 3A as a block“T”, to compensate for the bias to the above and left blocks used togenerate spatial neighboring candidates. However, if that block islocated outside of the current CTB (or LCU) row or motion information isnot available, the block is substituted with a center block of the PU. Amotion vector for a TMVP candidate is derived from the co-located PU ofthe co-located picture, indicated in the slice level. Similar totemporal direct mode in AVC, a motion vector of the TMVP candidate maybe subject to motion vector scaling, which is performed to compensatefor distance differences.

Other aspects of motion prediction are covered in the HEVC standard. Forexample, several other aspects of merge and AMVP modes are covered. Oneaspect includes motion vector scaling. With respect to motion vectorscaling, it can be assumed that the value of motion vectors isproportional to the distance of pictures in the presentation time. Amotion vector associates two pictures—the reference picture and thepicture containing the motion vector (namely the containing picture).When a motion vector is utilized to predict the other motion vector, thedistance of the containing picture and the reference picture iscalculated based on the Picture Order Count (POC) values.

For a motion vector to be predicted, both its associated containingpicture and reference picture may be different. Therefore, a newdistance (based on POC) is calculated. And, the motion vector is scaledbased on these two POC distances. For a spatial neighboring candidate,the containing pictures for the two motion vectors are the same, whilethe reference pictures are different. In HEVC, motion vector scalingapplies to both TMVP and AMVP for spatial and temporal neighboringcandidates.

Another aspect of motion prediction includes artificial motion vectorcandidate generation. For example, if a motion vector candidate list isnot complete, artificial motion vector candidates are generated andinserted at the end of the list until all candidates are obtained. Inmerge mode, there are two types of artificial MV candidates: combinedcandidate derived only for B-slices; and zero candidates used only forAMVP if the first type does not provide enough artificial candidates.For each pair of candidates that are already in the candidate list andthat have necessary motion information, bi-directional combined motionvector candidates are derived by a combination of the motion vector ofthe first candidate referring to a picture in the list 0 and the motionvector of a second candidate referring to a picture in the list 1.

In some implementations, a pruning process can be performed when addingor inserting new candidates into an MV candidate list. For example, insome cases it is possible for MV candidates from different blocks toinclude the same information. In such cases, storing duplicative motioninformation of multiple MV candidates in the MV candidate list can leadto redundancy and a decrease in the efficiency of the MV candidate list.In some examples, the pruning process can eliminate or minimizeredundancies in the MV candidate list. For example, the pruning processcan include comparing a potential MV candidate to be added to an MVcandidate list against the MV candidates which are already stored in theMV candidate list. In one illustrative example, the horizontaldisplacement (Δx) and the vertical displacement (Δy) (indicating aposition of a reference block relative to a position of the currentblock) of a stored motion vector can be compared to the horizontaldisplacement (Δx) and the vertical displacement (Δy) of the motionvector of a potential candidate. If the comparison reveals that themotion vector of the potential candidate does not match any of the oneor more stored motion vectors, the potential candidate is not consideredas a candidate to be pruned and can be added to the MV candidate list.If a match is found based on this comparison, the potential MV candidateis not added to the MV candidate list, avoiding the insertion of anidentical candidate. In some cases, to reduce complexity, only a limitednumber of comparisons are performed during the pruning process insteadof comparing each potential MV candidate with all existing candidates.

There are various related motion-prediction technologies. One predictiontechnology is illumination compensation (IC) or luminance compensation(also referred to in some cases as local illumination compensation(LIC)). The terms illumination compensation (IC) and local illuminationcompensation (LIC) are used interchangeably herein. IC was proposed forHEVC. For example, in JCTVC-C041, Partition Based IlluminationCompensation (PBIC) was proposed. Different from weighted prediction(WP), which enables and/or disables WP, and signals WP parameters at theslice level (as described below), PBIC enables and/or disables IC andsignals IC parameters at the prediction unit (PU) level to handle localillumination variation. In JVET-B0023, the block-based IC is extended tothe CU, and similar to the PU in HEVC, the CU becomes the basic unitwhich carries the motion information in the QTBT structure.

Similar to Weighted Prediction (WP), which is described in more detailbelow, a scaling factor (also denoted by a) and an offset (also denotedby b) is used in IC, and the shift number is fixed to be 6. An IC flagis coded for each PU to indicate whether IC applies for current PU ornot. If IC applies for the PU, a set of IC parameters (e.g., a and b)are signaled to the decoder and is used for motion compensation. In someexamples, to save bits spent on IC parameters, the chroma componentshares the scaling factors with luma component and a fixed offset 128 isused.

In 3D-HEVC, IC is enabled for inter-view prediction. Different from WPand PBIC, which signals IC parameters explicitly, IC derives ICparameters based on neighboring samples of current CU and neighboringsamples of reference block. In some cases, IC applies to the 2N×2Npartition mode only. In some examples, for AMVP mode, one IC flag issignaled for each CU that is predicted from an inter-view referencepicture. In some examples, for merge mode, to save bits, an IC flag issignaled only when the merge index of the PU is not equal to 0. In somecases, IC does not apply to CU that is only predicted from temporalreference pictures.

With respect to derivation of IC parameters, the linear IC model used ininter-view prediction is shown in Equation (1):

p(i,j)=a*r(i+dv _(x) ,j+dv _(y))+b, where (i,j)∈PU _(c)  Equation (1)

In Equation (1), PU_(c) is the current PU, (i,j) is the coordinate ofpixels in PU_(c), (dv_(x), dv_(y)) is the disparity vector of PU_(c),p(i, j) is the prediction of PU, r is the PU's reference picture fromthe neighboring view, and a and b are parameters of the linear IC model.

To estimate parameter a and b for a PU, two sets of pixels, as shown inFIG. 4A and FIG. 4B are used. The first set of pixels are shown in FIG.4A and include available reconstructed neighboring pixels in a leftcolumn and an above row of the current CU (the CU that contains thecurrent PU). The second set of pixels are shown in FIG. 4B and includecorresponding neighboring pixels of the current CU's reference block.The reference block of the current CU is found by using the current PU'sdisparity vector.

Let Rec_(neig) and Rec_(refneig) denote the neighboring pixel set of thecurrent CU and its reference block, respectively, and let 2N denote thepixel number in Rec_(neig) and Rec_(refneig). Then, a and b can becalculated as:

$\begin{matrix}{a = \frac{\begin{matrix}{{2{N \cdot {\sum\limits_{i = 0}^{{2N} - 1}{{{Rec}_{neig}(i)} \cdot {{Rec}_{refneig}(i)}}}}} - {\sum\limits_{i = 0}^{{2N} - 1}{{{Rec}_{neig}(i)} \cdot}}} \\{\sum\limits_{i = 0}^{{2N} - 1}{{Rec}_{refneig}(i)}}\end{matrix}}{\begin{matrix}{{2{N \cdot {\sum\limits_{i = 0}^{{2N} - 1}{{{Rec}_{refneig}(i)} \cdot {{Rec}_{refneig}(i)}}}}} -} \\( {\sum\limits_{i = 0}^{{2N} - 1}{{Rec}_{refneig}(i)}} )^{2}\end{matrix}}} & {{Equation}\mspace{14mu} (2)} \\{\mspace{79mu} {b = \frac{{\sum\limits_{i = 0}^{{2N} - 1}{{Rec}_{neig}(i)}} - {a \cdot {\sum\limits_{i = 0}^{{2N} - 1}{{Rec}_{refneig}(i)}}}}{2N}}} & {{Equation}\mspace{14mu} (3)}\end{matrix}$

In some cases, only a is used in the linear model and b is always setequal to 0. In some cases, only b is used and a is always set equal to1.

In HEVC, Weighted Prediction (WP) is supported, in which case a scalingfactor (denoted by a), a shift number (denoted by s) and an offset(denoted by b) is used in the motion compensation. Suppose the pixelvalue in position (x, y) of the reference picture is p(x, y), then p′(x,y)=((a*p(x, y)+(1<<(s−1)))>>s)+b instead of p(x, y) is used as theprediction value in motion compensation.

When WP is enabled, for each reference picture of current slice, a flagis signaled to indicate whether WP applies for the reference picture ornot. If WP applies for one reference picture, a set of WP parameters(i.e., a, s and b) is sent to the decoder and is used for motioncompensation from the reference picture. In some examples, to flexiblyturn on/off WP for luma and chroma component, WP flag and WP parametersare separately signaled for luma and chroma component. In WP, one sameset of WP parameters is used for all pixels in one reference picture.

A local illumination compensation (LIC) method was also proposed in JEM.A description of LIC in JEM can be found in JVET-G1001. With respect toLIC in JEM, LIC is based on a linear model for illumination changes,using a scaling factor a and an offset b. Such LIC is enabled ordisabled adaptively for each coded coding unit (CU) for whichinter-prediction mode has been applied. When LIC applies for a CU, aleast square error method is employed to derive the parameters a and bby using the neighboring samples of the current CU and theircorresponding reference samples. For example, as illustrated in FIG. 5Aand FIG. 5B, the subsampled (e.g., 2:1 subsampling) neighboring samplesof the CU and the corresponding pixels (identified by motion informationof the current CU or sub-CU) in the reference picture are used. In someexamples, the IC parameters are derived and applied for each predictiondirection separately. In some examples, an illumination compensationflag can be signalled for a CU to indicate whether LIC applies or not.In some examples, such as when a CU is coded with merge mode, theillumination compensation flag may be copied from neighboring blocks, ina way similar to motion information copy in merge mode.

According to LIC, the luminance value (of a sample, or pixel) iscompensated for in inter-prediction in a linear form, a*p+b, where p isa sample in inter-prediction, a is a scaling factor, and b is an offset.The scaling factor a and offset b are the parameters derived usingneighboring samples of the current block and neighboring samples of thereference block (e.g., as shown in FIG. 5A and FIG. 5B), which is usedfor inter-prediction. For example, inter-prediction can first be derivedusing motion information signaled for an inter-coded block, then ICparameters a and b can be derived, and prediction refinement can then beperformed. The IC parameters can be derived by minimizing the differencebetween the neighboring reconstructed samples of the current block andthe neighboring samples of the reference block used forinter-prediction. In some cases, the minimization can be performed usinga linear least squares method and/or any other suitable minimizationmethod.

FIG. 6 is a diagram illustrating an example of neighbor reconstructedsamples of a current block 602 and neighbor samples of a reference block604 used for uni-directional inter-prediction. A motion vector MV can becoded for the current block 602, where the MV can include a referenceindex to a reference picture list and/or other motion information foridentifying the reference block 604. For example, the MV can include ahorizontal and a vertical component that provides an offset from thecoordinate position in the current picture to the coordinates in thereference picture identified by the reference index.

FIG. 7 is a diagram illustrating an example of neighbor reconstructedsamples of a current block 702 and neighbor samples of a first referenceblock 704 and a second reference block 706 used for bi-directionalinter-prediction. In this case, two motion vectors MV0 and MV1 can becoded for the current block 702 to identify the first reference block704 and a second reference block 706, respectively.

As described above, IC parameters can include one or more offsets (e.g.,offset b), one or more weights or scaling factors (e.g., scaling factora), a shift number, and/or other suitable illumination compensationparameters. IC parameters can be derived for inter-prediction (e.g.,uni-directional inter-prediction). For bi-directional inter-prediction,the one or more weights can include a first weight for the firstreference picture and a second weight for the second reference picture.

In some implementations, a linear least square regression can be used toestimate the IC parameters in bi-predictive motion compensation. In oneexample, the derivation of the IC parameters can be performed by solvinga cost function. For example, the cost function can include using aleast-square function. For instance, a subset of samples from one ormore neighboring blocks of the current block can be used to derive theIC parameters. Samples from neighboring blocks of the current block canbe used to find a possible illuminance changes in the current block 702,because it can be assumed that there is a strong correlation between theneighboring samples (in the neighboring blocks) and the current samples(in the current block 702). For instance, it can be assumed that thecurrent block and the neighboring block, which share the same motioninformation, should contain very similar illuminance values. Anotherreason to use neighboring samples is that the current block has not yetbeen predicted, and there may not be pixels to use from the currentblock, in which case the neighboring samples (which have beenreconstructed) can be used in performing the motion compensation of thecurrent block.

In one illustrative example, either a top neighbor, a left neighbor, orboth top neighbor and the left neighbor may be used. For instance, aftersubsampling, a subset of samples from a top neighbor and a left neighbor(Ni) for the current block 702, a subset of pixels from a top neighborand a left neighbor (P0) of the first reference block 704, and a subsetof pixels from a top neighbor and a left neighbor (P1) of the secondreference block 706 can be used in deriving the IC parameters for thecurrent block 702. The samples of the neighboring blocks P0 and P1 caninclude samples corresponding to the neighboring samples of theneighboring blocks Ni. In some cases, the corresponding samples used inthe neighboring blocks P0 and P1 can be identified by motion informationof the current block. In one illustrative example, the motion vectorscan be signaled through either the merge mode or the AMVP mode. Thereference pictures can be identified using their reference indexes, thereference blocks 704 and 706 within the reference pictures using themotion vectors MV0 and MV1, respectively.

In some examples, more than one derivation method to derive the ICparameters can be performed. An example of an inter-prediction engine ormodule for deriving the IC parameters at the encoder side can includethe prediction processing unit 41, the motion estimation unit 42, and/orthe motion compensation unit 44 shown in FIG. 11. An example of aninter-prediction engine or module for deriving the IC parameters at thedecoder side can include the prediction processing unit 81 and/or themotion compensation unit 82 shown in FIG. 11. In such examples, theencoder or other transmitter-side device can signal to the decoder whichderivation method is to be used at a sequence level (e.g., in the VPSand/or the SPS), at the picture level (e.g., in the PPS), at the slicelevel (e.g., in the slice header), at the CTU level, at CU level, at PUlevel, or a combination thereof, or other suitable signaling level.

In some examples, the least square solution can be calculated based onmultiple lines and/or columns of a neighbor (e.g., either top neighbor,a left neighbor, both the top and left neighbors, or other neighbors).Example numbers (and in some cases, the typical numbers) of lines and/orcolumns includes one, two, four, or any other suitable number of rowsand/or columns. The cost functions mentioned above may be modified whenmultiple lines and/or columns of the neighboring block are used. Forexample, if the blocks are 16×16 blocks (16 rows of pixels by 16 columnsof pixels), and if two lines from the top neighboring block and twocolumns from the left neighboring block are used, the neighboring blockN_(i) will include 64 samples (32 samples from the left neighboringblock and 32 samples from the top neighboring block). In such anexample, the neighbors P0 and P1 will also include 64 samples.

In some cases, integer-positioned samples (or pixels) are used for thederivation of the IC parameters. In some cases, fractional-positionedsamples are used for the derivation of the IC parameters. In some cases,integer-positioned samples and fractional-positioned samples can both beused. For example, the true displacements of moving objects betweenpictures are continuous and tend to not follow the sampling grid of thepictures in a video sequence. Because of this, fractional accuracy canbe used for motion vectors instead of integer accuracy, leading to adecrease in residual error and an increase in coding efficiency of videocoders. If a motion vector has a fractional value, the reference blockneeds to be interpolated accordingly. For example, a motion vector for asample of a current block can point to a fractional-pel position in areference block. A fractional-pel position refers to samples (e.g., aluma sample) at fractional sample locations (non-integer locations) inthe block. Such locations need to be generated by interpolation. In oneexample when factional-positioned samples are used, an interpolated orfiltered version of the reference block neighbors (e.g., P0 or P1) canbe used to reduce the quantization error from the reconstructed pixelswhen deriving the LIC parameters. Such an interpolated version of atemplate can be generated using one or more interpolation filters.

In some examples, only the luma component needs to be used to jointlyoptimize the IC parameters for both Ref0 and Ref1. Alternatively, bothluma and chroma components can be considered during the derivation ofthe bi-predictive LIC parameters. The encoder can signal to the decoder(in a parameter set, in an SEI message, or other suitable signalingmechanism) whether or not to apply LIC to one or more of the chromacomponents, or only to apply LIC to the luma components.

In some examples, one or more flags can be signaled (e.g., at a blocklevel, slice level, or other suitable level), such as from an encoder toa decoder, to indicate whether particular tools have been applied (e.g.,LIC, merge mode, among others) in the prediction of a block. Forexample, a merge mode flag can be stored with motion information for acurrent block. Whether the current block has been coded using merge modecan be inferred from the motion information based on the merge modeflag. In addition to the merge mode flag, an illumination compensation(IC) flag can also be used to indicate that a block (e.g., a PU, CU, orother block) has been coded with illumination compensation applied. Asnoted above, when a block is coded with merge mode, the IC flag can becopied from neighboring blocks, in a way similar to motion informationcopy in merge mode. Otherwise, if the CU has not been coded with mergemode (e.g., an AMVP mode was used instead), an IC flag can be signalledfor the CU to indicate whether LIC applies or not.

As described in the JVET literature (e.g., JVET-K0556), the VVC TestModel (VTM) 3.0 (VTM-3.0) adopts a coding unit (CU) split restrictionregarding the concept of a square-shaped virtual pipeline data unit(VPDU). VPDUs are non-overlapping cells in a picture or video frame. Forexample, VPDUs can be non-overlapping M×M-luma(L)/N×N-chroma(C) units ina picture. The VPDU construct includes virtual blocks that are used formemory access (e.g., to determine which area of memory is used forprocessing a particular block or blocks of data), defining the size ofthe memory allocated to implement the Standard-based coding process(e.g., HEVC, VVC, or other coding process). The VPDU construct is not ablock partitioning mechanism for coding purposes. For instance, in thehardware decoding process, consecutive VPDUs can be processed inparallel by multiple processing/decoding pipeline stages (e.g.,different decoding pipeline stages process different VPDUssimultaneously). In some cases, a VPDU size can be roughly proportionalto the buffer size in some pipelines. For instance, a VPDU size can beset to the size of a transform block (TB) size. In one illustrativeexample, the size of a VPDU can be 64×64 samples (e.g., luma samples).In HEVC, the VPDU size is set to maximum transform block size which is32×32-L (Luma samples) and 16×16-C(Chroma samples). In VVC, the VPDUsize is set to 128×128-L (Luma samples) and 64×64-C(Chroma samples),which results in the request of larger VPDU sizes.

A VPDU can contain one or more multiple blocks (e.g., a CU, PU, TU, orother block). For example, in some cases, a single CU can be included inone VPDU (e.g., the size of the CU and the VPDU size are the same). FIG.8 is a diagram illustrating an example of a VPDU 811 containing a singlecurrent block 802. The current block 802 can be a CU, a PU, a TU, orother block of a picture. Also shown in FIG. 8 are top neighboringsamples 812 and the left neighboring samples 814 of the current block802. The top neighboring samples 812 are included in one or more blocksthat are immediately above the current block 802. The left neighboringsamples 814 are included in one or more blocks that are immediately tothe left of the current block 802. The top neighboring samples 812 andthe left neighboring samples 814 can be used to perform illuminationcompensation (IC) for the current block 802, as described above.

In some cases, multiple blocks can be included in one VPDU (e.g.,multiple CUs, PUs, TUs, or other blocks having sizes that are smallerthan the VPDU size). FIG. 9 is a diagram illustrating an example of aVPDU 911 containing four blocks, including a first block 920, a secondblock 922, a third block 924, and a fourth block 926. Each of the firstblock 920, the second block 922, the third block 924, and/or the fourthblock 926 can be a CU, a PU, a TU, or other block of a picture. Topneighboring samples 912 and left neighboring samples 914 of the firstblock 920, the second block 922, the third block 924, and the fourthblock 926 are also shown, which can be used for performing IC for thevarious blocks, as described above.

Depending on the size of a block (e.g., a CU, PU, TU, or other block),the block may or may not span multiple VPDUs (in which case a block mayinclude multiple VPDUs). For example, a block having a size of 128×64(128 samples wide×64 samples high) can span two VPDUs that each have asize of 64×64. In another example, a block having a size of 128×128 (128samples wide×128 samples high) can span four VPDUs that each have a sizeof 64×64. The block can be split into a certain number of sub-blocks forperforming inter-prediction by each of the VPDU pipeline stages. Forexample, a 128×128 block can be split into for 64×64 sub-blocks forprocessing by four different VPDU pipeline stages. The block can besplit for inter-prediction because there is no dependency on neighboringblocks for performing inter-prediction.

FIG. 10 is a diagram illustrating an example of current block 1002spanning multiple VPDUs. For example, the current block 1002 containsthe samples associated with four VPDUs, including a first VPDU 1030, asecond VPDU 1032, a third VPDU 1034, and a fourth VPDU 1036. In oneillustrative example, the current block 1002 has a size of 128×128, andeach of the VPDUs 1030-1034 have a size of 64×64. The current block 1002can be a CU, a PU, a TU, or other block of a picture. Top neighboringsamples 1012 and left neighboring samples 1014 of the current block 1002are also shown in FIG. 10, which can be used for performing IC for thecurrent block 1002.

FIG. 11 is a diagram illustrating the relationship of neighboringsamples used for IC when a block is a same size as a VPDU. For example,as shown in FIG. 11, a current block 1102 fits within a VPDU 1111 due tothe current block 1102 and the VPDU 1111 being of a same size. Thecurrent block 1102 can be a CU, a PU, a TU, or other block of a picture.Top neighboring samples 1112 are included in one or more blocks that areimmediately above the current block 1102. Left neighboring samples 1114are included in one or more blocks that are immediately to the left ofthe current block 1102. The motion compensation (MC) access memory 1110is the memory area corresponding to the VPDU containing the referenceblock for the current block 1102. The top neighboring samples 1116 andthe left neighboring samples 1118 of the reference block 1104 areincluded in the MC access memory 1110 area of the current block 1102.The top neighboring samples 1116 are included in one or more blocks thatare immediately above the reference block 1104, and the left neighboringsamples 1118 are included in one or more blocks that are immediately tothe left of the reference block 1104. Using the IC techniques describedabove, the top neighboring samples 1112 and the left neighboring samples1114 of the current block 1102, as well as the top neighboring samples1116 and the left neighboring samples 1118 of the reference block 1104,can be used to perform IC for the current block 1102.

Because the top neighboring samples 1116 and the left neighboringsamples 1118 of the reference block 1104 are included in the MC accessmemory 1110 area, there is no additional impact to the memory bandwidthwhen IC is performed using the top neighboring samples 1116 and the leftneighboring samples 1118, and thus there is no increase in the number ofVPDU pipeline stage cycles that are needed to perform IC for the currentblock 1102.

As noted above, a block (e.g., a CU, PU, or other block) can be splitinto a certain number of sub-blocks (e.g., by a decoding device) forperforming inter-prediction by each of the VPDU pipeline stages becausethere is no dependency on neighboring blocks for performinginter-prediction. However, because IC uses neighboring blocks todetermine IC parameters, there is a dependency on neighboring blockswhen IC is used along with inter-prediction. Additional VPDU processingpipelines may thus be needed when performing IC. For example, when ablock covers more than one VPDU, such as the example illustrated in FIG.10, neighboring samples used for IC parameter calculation for the block(e.g., for calculating one or more offsets b and/or one or more weightsor scaling factors a) lead to the need for additional memory access andto increased bandwidth usage. FIG. 12 shows the relationship of theneighboring samples when a block covers more than one VPDU. For example,a current block 1202 includes the samples associated with four VPDUs,including a first VPDU 1230, a second VPDU 1232, a third VPDU 1234, anda fourth VPDU 1236. The current block 1202 can be a CU, a PU, a TU, orother block of a picture. Top neighboring samples 1212 (from one or moreblocks immediately above the current block 1102) and left neighboringsamples 1214 (from one or more blocks immediately to the left of thecurrent block 1102) are also shown.

The MC access memory 1210 is the memory area corresponding to the firstVPDU 1230 (e.g., the MC access memory 1210 area stores the samples thatare assigned to the first VPDU 1230). The MC access memory 1210 area ofthe first VPDU 1230 includes samples from the neighboring area aroundthe reference block 1204 of the first VPDU 1230. For example, as shownin FIG. 12, the top neighboring samples 1216 (from one or more blocksimmediately above the reference block 1204) and the left neighboringsamples 1218 (from one or more blocks immediately to the left of thereference block 1204) of the reference block 1204 of the first VPDU 1230are included in the MC access memory 1210 area of the first VPDU 1230.However, as indicated by the two “X's” in FIG. 12, the MC access memory1210 area of the first VPDU 1230 does not include reference samples fromthe neighboring area around reference blocks of the second VPDU 1232,the third VPDU 1234, or the fourth VPDU 1236. However, these referencesamples may be needed to determine the IC parameters required to performIC for the current block 1202 (e.g., when IC requires all neighboringsamples from a top neighboring block of the current block 1202 and allneighboring samples from a left neighboring block of the current block1202). Therefore, some of the neighboring samples used for performing ICparameter calculation for the current block 1202 require additionalmemory access and increase the bandwidth of the processing stageassociated with the first VPDU 1230 by requiring the use of the pipelinestages associated with the second VPDU 1232 and the third VPDU 1234.

In some cases, only the top and left neighboring samples of a first VPDUof both the current block and the reference block of the current blockare used to determine IC parameters for a current block, which wasdiscussed in JVET-M0088. FIG. 13 is a diagram illustrating an example ofsuch a case. For example, a current block 1302 includes the samplesassociated with a first VPDU 1330, a second VPDU 1332, a third VPDU1334, and a fourth VPDU 1336. The current block 1302 can be a CU, a PU,a TU, or other block of a picture. Top neighboring samples 1312 from oneor more blocks immediately above the first VPDU 1330 and leftneighboring samples 1314 from one or more blocks immediately to the leftof the first VPDU 1330 are also shown. The top neighboring samples 1312can include a row of samples from a block that is immediately above thefirst VPDU 1330 (e.g., a bottom-most row of samples from the topneighboring block above the current block 1302, where the bottom-mostrow of samples is adjacent to a top-most row of samples in the currentblock 1302). The left neighboring samples 1314 can include a column ofsamples from a block that is immediately to the left of the first VPDU1330 (e.g., a right-most column of samples from the left neighboringblock to the left of the current block 1302, where the right-most columnof samples is adjacent to a left-most column of samples in the currentblock 1302).

As noted above in the example of FIG. 12, the MC access memory 1310 areaof the first VPDU 1330 includes samples from the neighboring one or moreblocks adjacent to the reference block 1304 of the first VPDU 1330,including for example the top neighboring samples 1316 and the leftneighboring samples 1318 of the reference block 1304 of the first VPDU1330. Using the technique described in JVET-M0088, the top neighboringsamples 1316 and the left neighboring samples 1318 of the referenceblock 1304 of the first VPDU 1330 and the top neighboring samples 1312and the left neighboring samples 1314 of the first VPDU 1330 are used tocalculate IC parameters for the current block 1302. Using such atechnique, neighboring samples of the second VPDU 1332, the third VPDU1334, and the fourth VPDU 1336 included in the current block 1302 andthe neighboring samples of the reference blocks of the VPDUs 1332, 1334,and 1336 are not used to calculate the IC parameters for the currentblock 1302. In such cases, the first VPDU 1330 shares the calculated ICparameter with the second VPDU 1332, the third VPDU 1334, and the fourthVPDU 1336 in the current block 1302. For example, the pipeline stagesused for coding the samples associated with the second VPDU 1332, thethird VPDU 1334, and the fourth VPDU 1336 can use the IC parametersdetermined by the pipeline stage used for coding the samples associatedwith the first VPDU 1330. However, using only the top neighboringsamples and the left neighboring samples of the first VPDU 1330 of boththe current block 1302 and the reference block 1304 may reduce thecoding performance of IC because less neighbouring samples are used fordetermining the IC parameters for the entire block 1302.

Systems, methods, and computer-readable media are described herein forimproving illumination compensation. The techniques described herein canbe performed individually or in any combination.

In some examples, techniques are described for disabling IC (e.g., localillumination compensation (LIC)) for a block that covers more than oneVPDU (e.g., a plurality a VPDUs). For example, if the size of a VPDU is64×64 (64 samples×64 samples), then LIC is disabled for blocks with awidth larger than 64 samples and/or a height larger than 64 samples(corresponding to a block that covers more than one 64×64 VPDU). In suchexamples, for a block that covers more than one VPDU, the LIC flag maynot be signalled and can be inferred (e.g., during a decoding process bya decoder, an encoder or other device or component) to have a value of 0(indicating LIC is not performed for that block).

In some examples, techniques are described for selectively using certainsamples for coding (e.g., for performing LIC). For example, if a blockcovers more than one VPDU, in addition to using the top and leftneighboring samples of a VPDU of both a current block and a referenceblock of the current block, additional neighbor samples can be used fordetermining illumination compensation (IC) parameters for the currentblock.

In some cases, subsampling (also referred to as down-sampling) is notapplied to neighboring samples (e.g., the top neighboring samples and/orthe left neighboring samples) of a first VPDU of either (or both in somecases) the current block and the reference block, as is done in theexamples described above with respect to FIG. 5A—FIG. 7. For instance,referring to FIG. 13, a coding device (e.g., the encoding device 104and/or the decoding device 112) can determine that the current block1302 covers more than one VPDU (the first VPDU 1330, the second VPDU1332, the third VPDU 1334, and the fourth VPDU 1336). In response todetermining the current block 1302 covers more than one VPDU, the codingdevice can determine to calculate IC parameters for the current block1302 using the top neighboring samples 1316 and the left neighboringsamples 1318 of the reference block 1304 of the first VPDU 1330 and thetop neighboring samples 1312 and the left neighboring samples 1314 ofthe first VPDU 1330. Further in response to determining the currentblock 1302 covers more than one VPDU, the coding device can determinenot to perform subsampling to the top neighboring samples 1316 of thereference block 1304 of the first VPDU 1330, the left neighboringsamples 1318 of the reference block 1304, the top neighboring samples1312 of the first VPDU 1330, and/or the left neighboring samples 1314 ofthe first VPDU 1330. By determining not to perform subsampling for theneighboring samples, more samples will be used for determining the ICparameters for the current block 1302.

In another implementations, in addition to or as an alternative todetermining not to perform subsampling for neighboring samples,additional neighbor samples from more lines and/or columns of the topneighboring samples and/or left neighboring samples of a VPDU of eitheror both the current and the reference blocks can be used, if thoseadditional neighboring samples are available. In some cases, theadditional neighbor samples can include samples from an additional rowof samples from a neighboring block of the VPDU included in a currentblock, an additional column of samples from the neighboring block of theVPDU, an additional row of samples from the neighboring block of thereference block of the current block, an additional column of samplesfrom the neighboring block of the reference block, samples from aneighboring block of an additional VPDU included in the current block,or any combination thereof.

For instance, assuming the top neighboring samples of a first VPDU ofthe current block include a first row of samples from a top neighboringblock that is immediately above the first VPDU, the left neighboringsamples of the first VPDU include a first column of samples from a leftneighboring block that is immediately to the left of the first VPDU, thetop neighboring samples of a first reference block of the first VPDUinclude a first row of samples from a top neighboring block that isimmediately above the reference block, and the left neighboring samplesof the first reference block of the first VPDU include a first column ofsamples from a left neighboring block that is immediately to the left ofthe reference block, the additional neighbor samples can include samplesfrom a second row of samples from the top neighboring block of the firstVPDU, a second column of samples from the left neighboring block of thefirst VPDU, a second row of samples from the top neighboring block ofthe reference block, a second column of samples from the leftneighboring block of the reference block, samples from a neighboringblock of a second VPDU included in the current block, or any combinationthereof.

FIG. 14 is a diagram illustrating an example of determining ICparameters for a current block 1402 using multiple rows (or lines) ofsamples from a top neighboring block (or multiple top neighboringblocks) and multiple columns of samples from a left neighboring block(or multiple left neighboring blocks) of a first VPDU 1430 of thecurrent block 1402, and using multiple rows of samples from a topneighboring block (or multiple top neighboring blocks) and multiplecolumns of samples from a left neighboring block (or multiple leftneighboring blocks) of a reference block 1404 of the first VPDU 1430.The current block 1402 can be a CU, a PU, a TU, or other block of apicture. The current block 1402 includes multiple VPDUs, including thefirst VPDU 1430, a second VPDU 1432, a third VPDU 1434, and a fourthVPDU 1436.

As shown in FIG. 14, a first row of samples 1442 from a top neighboringblock (or from multiple top neighboring blocks) that is adjacent to thefirst VPDU 1430 and a second row of samples 1443 from the topneighboring block (or multiple top neighboring blocks) are identified(e.g., by a coding device, such as the encoding device 104 and/or thedecoding device 112) for use in determining IC parameters for thecurrent block 1402. The first row of samples 1442 can include abottom-most row of samples from the top neighboring block above thefirst VPDU 1430, and can be located immediately above a top-most row ofsamples in the current block 1402. The second row of samples 1443 caninclude a row of samples that is immediately above the first row ofsamples 1442. In addition, a first column of samples 1444 from a leftneighboring block (or from multiple left neighboring blocks) that isadjacent to the first VPDU 1430 and a second column of samples 1445 fromthe left neighboring block (or multiple left neighboring blocks) aredetermined for use in determining the IC parameters for the currentblock 1402. The first column of samples 1444 can include a right-mostcolumn of samples from the left neighboring block to the left of thefirst VPDU 1430, and can be located immediately to the left of aleft-most column of samples in the current block 1402. The second columnof samples 1445 can include a column of samples that is immediately tothe left of the first column of samples 1444.

A reference block 1404 of the first VPDU 1430 is located using a motionvector 1405. The motion vector 1405 can be determined using any suitabletechnique used in inter-prediction (e.g., merge mode, advanced motionvector prediction (AMVP) mode, skip mode, and/or other inter-predictiontechnique), such as those described herein. The coding device candetermine a first row of samples 1446 from a top neighboring block (orfrom multiple top neighboring blocks) that is adjacent to the referenceblock 1404 and a second row of samples 1447 from the top neighboringblock (or multiple top neighboring blocks) for use in determining the ICparameters for the current block 1402. The first row of samples 1446 caninclude a bottom-most row of samples from the top neighboring blockabove the reference block 1404, and can be located immediately above atop-most row of samples in the reference block 1404. The second row ofsamples 1447 can include a row of samples (in the top neighboring blockabove the reference block 1404) that is immediately above the first rowof samples 1446. The coding device can also determine a first column ofsamples 1448 from a left neighboring block (or from multiple leftneighboring blocks) that is adjacent to the reference block 1404 and asecond column of samples 1449 from the left neighboring block (ormultiple left neighboring blocks) of the reference block 1404 for use indetermining the IC parameters for the current block 1402. The firstcolumn of samples 1448 can include a right-most column of samples fromthe left neighboring block to the left of the reference block 1404, andcan be located immediately to the left of a left-most column of samplesin the reference block 1404. The second column of samples 1449 caninclude a column of samples (from the left neighboring block to the leftof the reference block 1404) that is located immediately to the left ofthe first column of samples 1448.

The first row of samples 1442, the second row of samples 1443, the firstcolumn of samples 1444, and the second column of samples 1445neighboring the first VPDU 1430 can be used as Rec_(neig) in Equations(2) and (3) above, and the first row of samples 1446, the second row ofsamples 1447, the first column of samples 1448, and the second column ofsamples 1449 neighboring the reference block 1404 can be used asRec_(refneig) in Equations (2) and (3) above, and/or can be used byanother IC parameter derivation technique (e.g., the LIC method proposedin JEM), to determine the IC parameters for the first VPDU 1430. In somecases, the first VPDU 1430 can share the calculated IC parameter withthe second VPDU 1432, the third VPDU 1434, and the fourth VPDU 1436 inthe current block 1402. For example, the pipeline stages used for codingthe samples associated with the second VPDU 1432, the third VPDU 1434,and the fourth VPDU 1436 can use the IC parameters determined by thepipeline stage used for coding the samples associated with the firstVPDU 1430.

As shown in FIG. 14, the MC access memory 1410 area of the first VPDU1430 includes the first row of samples 1446, the second row of samples1447, the first column of samples 1448, and the second column of samples1449 neighboring the reference block 1404. Because the first row ofsamples 1446, the second row of samples 1447, the first column ofsamples 1448, and the second column of samples 1449 neighboring thereference block 1404 are included in the MC access memory 1410 areaassociated with the first VPDU 1430, there is no additional impact tothe memory bandwidth when IC is performed using these samples. Thus, theadditional samples can be used to determine IC parameters for thecurrent block 1402 without any increase in the number of VPDU pipelinestage cycles but with better coding performance of IC, such as whencompared to the number of VPDU pipeline stage cycles used and the ICperformance achieved when using the technique described in JVET-M0088 isperformed. For instance, better IC performance is achieved as comparedto the JVET-M0088 technique because more samples are used to derive theIC parameters using the example shown in FIG. 14.

While the example of FIG. 14 is shown to include the first row ofsamples 1442, the second row of samples 1443, the first column ofsamples 1444, and the second column of samples 1445 neighboring thefirst VPDU 1430, a coding device can determine to use anysub-combination of these samples for determining IC parameters for thecurrent block 1402. For example, the coding device can determine to usethe first row of samples 1442, the second row of samples 1443, and thefirst column of samples 1444. In another example, the coding device candetermine to use the first row of samples 1442, the first column ofsamples 1444, and the second column of samples 1445 neighboring thefirst VPDU 1430 for determining IC parameters for the current block1402. Similarly, while the example of FIG. 14 is shown to include thefirst row of samples 1446, the second row of samples 1447, the firstcolumn of samples 1448, and the second column of samples 1449neighboring the reference block 1404, the coding device can determine touse any sub-combination of the samples for determining IC parameters forthe current block 1402, such as the first row of samples 1446, thesecond row of samples 1447, and the first column of samples 1448. Inanother example, the coding device can determine to use the first row ofsamples 1446, the first column of samples 1448, and the second column ofsamples 1449 neighboring the reference block 1404 for determining ICparameters for the current block 1402. In yet another example, thecoding device can determine to use, for determining IC parameters forthe current block 1402, the first row of samples 1442, the second row ofsamples 1443, the first column of samples 1444, and the second column ofsamples 1445 neighboring the first VPDU 1430, and the first row ofsamples 1446 and the first column of samples 1448 neighboring thereference block 1404. In another example, the coding device candetermine to use the first row of samples 1442 and the first column ofsamples 1444 neighboring the first VPDU 1430, and the first row ofsamples 1446, the second row of samples 1447, the first column ofsamples 1448, and the second column of samples 1449 neighboring thereference block 1404 for determining IC parameters for the current block1402. One of ordinary skill will appreciate that other combinations ofthe first row of samples 1442 and the first column of samples 1444neighboring the first VPDU 1430, the first row of samples 1446 and thefirst column of samples 1448 neighboring the reference block 1404, andany of the additional samples (e.g., the second row of samples 1443and/or the second column of samples 1445 neighboring the first VPDU1430, and/or the second row of samples 1447 and/or the second column ofsamples 1449 neighboring the reference block 1404) can be used by acoding device to determine IC parameters for the current block 1402.

FIG. 15 is a diagram illustrating an example of determining samples foruse in calculating IC parameters for a current block 1502. The currentblock 1502 can be a CU, a PU, a TU, or other block of a picture. Thecurrent block 1502 includes multiple VPDUs, including a first VPDU 1530,a second VPDU 1532, a third VPDU 1534, and a fourth VPDU 1536. In theexample of FIG. 15, the IC parameters can be determined for the currentblock 1502 using at least one row and at least one column of samplesneighboring a first VPDU 1530 and at least one row and at least onecolumn of samples neighboring additional VPDUs (including a second VPDU1532 and a third VPDU 1534) of the current block 1502, and usingmultiple rows of samples from a top neighboring block (or multiple topneighboring blocks) and multiple columns of samples from a leftneighboring block (or multiple left neighboring blocks) of a referenceblock 1504 of the first VPDU 1530.

A coding device (e.g., the encoding device 104 and/or the decodingdevice 112) can identify, for use in determining the IC parameters forthe current block 1502, a first row of samples 1542 from a topneighboring block (or from multiple top neighboring blocks) that isadjacent to the first VPDU 1530 and a second row of samples 1543 fromthe top neighboring block (or multiple top neighboring blocks) or froman additional top neighboring block (or from additional multiple topneighboring blocks) adjacent to the second VPDU 1532. In some cases, thefirst row of samples 1542 and the second row of samples 1543 can be froma same top neighboring block that is adjacent to the first VPDU 1530 andthe second VPDU 1532. For instance, a bottom-most row of the topneighboring block above the first VPDU 1530 and the second VPDU 1532 caninclude the first row of samples 1542 and the second row of samples1543, which can be located immediately above a top-most row of samplesin the current block 1502. In some cases, the first row of samples 1542can be from a first top neighboring block and the second row of samples1543 can be from a second top neighboring block that is different fromthe first top neighboring block, in which case the first top neighboringblock is adjacent to the first VPDU 1530 and the second top neighboringblock is adjacent to the second VPDU 1532. For instance, a bottom-mostrow of the first top neighboring block above the first VPDU 1530 caninclude the first row of samples 1542 and can be located immediatelyabove the top-most row of samples in the current block 1502. In suchcases, a bottom-most row of the second top neighboring block above thesecond VPDU 1532 can include the second row of samples 1543 and can belocated immediately above the top-most row of samples in the currentblock 1502.

The coding device can also determine, for use in determining the ICparameters for the current block 1502, a first column of samples 1544from a left neighboring block (or from multiple left neighboring blocks)that is adjacent to the first VPDU 1530 and a second column of samples1545 from the left neighboring block (or multiple left neighboringblocks) or from an additional left neighboring block (or from additionalmultiple left neighboring blocks) adjacent to the third VPDU 1534. Insome cases, the first column of samples 1544 and the second column ofsamples 1545 can be from a same left neighboring block that is adjacentto the first VPDU 1530 and the third VPDU 1534. For example, aright-most column of the left neighboring block to the left of the firstVPDU 1530 and the third VPDU 1534 can include the first column ofsamples 1544 and the second column of samples 1545, which can be locatedimmediately to the left of a left-most column of samples in the currentblock 1502. In some cases, the first column of samples 1544 can be froma first left neighboring block and the second column of samples 1545 canbe from a second left neighboring block that is different from the firstleft neighboring block, in which case the first left neighboring blockis adjacent to the first VPDU 1530 and the second left neighboring blockis adjacent to the third VPDU 1534. For instance, a right-most column ofthe first left neighboring block to the left of the first VPDU 1530 caninclude the first column of samples 1544 and can be located immediatelyto the left of the left-most column of samples in the current block1502. In such cases, a right-most column of the second left neighboringblock to the left of the third VPDU 1534 can include the second columnof samples 1545 and can be located immediately to the left of theleft-most column of samples in the current block 1502.

The coding device can determine a reference block 1504 of the first VPDU1530, which can be located using a motion vector 1505. The motion vector1505 can be determined using any suitable technique used ininter-prediction (e.g., merge mode, advanced motion vector prediction(AMVP) mode, skip mode, and/or other inter-prediction technique), suchas those described herein. The coding device can determine, for use indetermining the IC parameters for the current block 1502, a first row ofsamples 1546 from a top neighboring block (or from multiple topneighboring blocks) that is adjacent to the reference block 1504 and asecond row of samples 1547 from the top neighboring block (or multipletop neighboring blocks). The first row of samples 1546 can include abottom-most row of samples from the top neighboring block above thereference block 1504. For example, the first row of samples 1546 can belocated immediately above a top-most row of samples in the referenceblock 1504. The second row of samples 1547 can include a row of samples(in the top neighboring block above the reference block 1504) that isimmediately above the first row of samples 1546. The coding device canalso determine a first column of samples 1548 from a left neighboringblock (or from multiple left neighboring blocks) that is adjacent to thereference block 1504 and a second column of samples 1549 from the leftneighboring block (or multiple top neighboring blocks) of the referenceblock 1504 for use in determining the IC parameters for the currentblock 1502. The first column of samples 1548 can include a right-mostcolumn of samples from the left neighboring block to the left of thereference block 1504, and can be located immediately to the left of aleft-most column of samples in the reference block 1504. The secondcolumn of samples 1549 can include a column of samples (from the leftneighboring block to the left of the reference block 1504) that islocated immediately to the left of the first column of samples 1548.

The first row of samples 1542 and the first column of samples 1544neighboring the first VPDU 1530, the second row of samples 1543neighboring the second VPDU 1532, and the second column of samples 1545neighboring the third VPDU 1534 can be used as Rec_(neig) in Equations(2) and (3) above, and the first row of samples 1546, the second row ofsamples 1547, the first column of samples 1548, and the second column ofsamples 1549 neighboring the reference block 1504 can be used asRec_(refneig) in Equations (2) and (3) above, and/or can be used by anyother IC parameter derivation technique (e.g., the LIC method proposedin JEM) to determine the IC parameters for the first VPDU 1530. Asdescribed above, the first VPDU 1530 can share the calculated ICparameter with the second VPDU 1532, the third VPDU 1534, and the fourthVPDU 1536 in the current block 1502.

Similar to that described with respect to FIG. 14, the MC access memory1510 area of the first VPDU 1530 shown in FIG. 15 includes the first rowof samples 1546, the second row of samples 1547, the first column ofsamples 1548, and the second column of samples 1549 neighboring thereference block 1504, and thus there is no additional impact to thememory bandwidth when IC is performed using these samples. Theadditional samples can be used to determine IC parameters for thecurrent block 1502 without any increase in the number of VPDU pipelinestage cycles and with better coding performance of IC because moresamples are used to derive the IC parameters, such as when compared tothe number of VPDU pipeline stage cycles used and the IC performanceachieved by using the JVET-M0088 technique.

While the example of FIG. 15 is shown to include the first row ofsamples 1542, the second row of samples 1543, the first column ofsamples 1544, and the second column of samples 1545 neighboring thefirst VPDU 1530, the second VPDU 1532, and the third VPDU 1534,respectively, a coding device can determine to use any sub-combinationof these samples for determining IC parameters for the current block1502. For example, the coding device can determine to use the first rowof samples 1542, the second row of samples 1543, and the first column ofsamples 1544 for determining IC parameters for the current block 1502.In another example, the coding device can determine to use the first rowof samples 1542, the first column of samples 1544, and the second columnof samples 1545 for determining IC parameters for the current block1502. While the example of FIG. 15 is also shown to include the firstrow of samples 1546, the second row of samples 1547, the first column ofsamples 1548, and the second column of samples 1549 neighboring thereference block 1504, the coding device can determine to use anysub-combination of the samples for determining IC parameters for thecurrent block 1502. For example, the first row of samples 1546, thesecond row of samples 1547, and the first column of samples 1548 can beused by the coding device to determine IC parameters for the currentblock 1502. In another example, the coding device can determine to usethe first row of samples 1546, the first column of samples 1548, and thesecond column of samples 1549 neighboring the reference block 1504 fordetermining IC parameters for the current block 1502. In yet anotherexample, the coding device can determine to use, for determining ICparameters for the current block 1502, the first row of samples 1542 andthe first column of samples 1544 neighboring the first VPDU 1530, thesecond row of samples 1543 neighboring the second VPDU 1532, and thesecond column of samples 1545 neighboring the third VPDU 1534, and thefirst row of samples 1546 and the first column of samples 1548neighboring the reference block 1504. In another example, the codingdevice can determine to use the first row of samples 1542 and the firstcolumn of samples 1544 neighboring the first VPDU 1530, and the firstrow of samples 1546, the second row of samples 1547, the first column ofsamples 1548, and the second column of samples 1549 neighboring thereference block 1504 for determining IC parameters for the current block1502. It will be appreciated that other combinations of the first row ofsamples 1542 and the first column of samples 1544 neighboring the firstVPDU 1530, the first row of samples 1546 and the first column of samples1548 neighboring the reference block 1504, and any of the additionalsamples (e.g., the second row of samples 1543 neighboring the secondVPDU 1532, the second column of samples 1545 neighboring the third VPDU1534, the second row of samples 1547 neighboring the reference block1504, and/or the second column of samples 1549 neighboring the referenceblock 1504) can be used by a coding device to determine IC parametersfor the current block 1502.

In some examples, if there are additional samples in the MC accessmemory of a VPDU other than those neighboring the reference block of theVPDU, those additional samples can be used to determine IC parametersfor a current block. For instance, if there are additional samples inthe MC access memory of the VPDU to the right of a top neighboring row(or line) of samples above the top-most row of samples of the referenceblock and/or below a left neighboring column of samples to the left of aleft-most column of samples of the reference block, one or more of thosepixels could be used in addition to corresponding samples neighboringthe current block.

FIG. 16 is a diagram illustrating an example of determining samples foruse in calculating IC parameters for a current block 1602 using suchadditional samples, where the additional samples are shown as grayblocks with a diagonal pattern. The current block 1602 can be a CU, aPU, a TU, or other block of a picture. The current block 1602 includes afirst VPDU 1630, a second VPDU 1632, a third VPDU 1634, and a fourthVPDU 1636. As described in more detail below, in the example of FIG. 15,the IC parameters can be determined for the current block 1602 using anadditional row of samples 1647 to the right of the reference block 1604and an additional column samples 1649 below the reference block 1604,and also an additional row of samples 1643 to the right of the firstVPDU 1630 and an additional column of samples 1645 below the first VPDU1630. The number of lines and/or columns of those additional samples canbe larger than one in some cases, as described below with respect toFIG. 17.

A coding device (e.g., the encoding device 104 and/or the decodingdevice 112) can identify, for use in determining the IC parameters forthe current block 1602, a first row of samples 1642 from a topneighboring block (or from multiple top neighboring blocks) that isadjacent to the first VPDU 1630 and a first column of samples 1644 froma left neighboring block (or from multiple left neighboring blocks) thatis adjacent to the first VPDU 1630. The first row of samples 1642 caninclude a bottom-most row of samples from the top neighboring blockabove the first VPDU 1630, and can be located immediately above atop-most row of samples in the current block 1602. The first column ofsamples 1644 can include a right-most column of samples from the leftneighboring block to the left of the first VPDU 1630, and can be locatedimmediately to the left of a left-most column of samples in the currentblock 1602.

The coding device can determine a reference block 1604 of the first VPDU1630 using a motion vector 1605, which can be determined using anysuitable technique used in inter-prediction (e.g., merge mode, advancedmotion vector prediction (AMVP) mode, skip mode, and/or otherinter-prediction technique), such as those described herein. The codingdevice can determine, for use in determining the IC parameters for thecurrent block 1602, a first row of samples 1646 from a top neighboringblock (or from multiple top neighboring blocks) that is adjacent to thereference block 1604 and a first column of samples 1648 from a leftneighboring block (or from multiple left neighboring blocks) that isadjacent to the reference block 1604. The first row of samples 1646 caninclude a bottom-most row of samples from the top neighboring blockabove the reference block 1604. For example, the first row of samples1646 can be located immediately above a top-most row of samples in thereference block 1604. The first column of samples 1648 can include aright-most column of samples from the left neighboring block to the leftof the reference block 1604, and can be located immediately to the leftof a left-most column of samples in the reference block 1604.

The coding device can determine that the additional row of samples 1647and the additional column of samples 1649 are available in the MC accessmemory 1610 of the first VPDU 1630, and can use the additional row ofsamples 1647 and the additional column of samples 1649 for determiningthe IC parameters for the current block 1602. In some cases, the firstrow of samples 1646 and the additional row of samples 1647 can be from asame top neighboring block (or from multiple blocks) that is adjacent tothe reference block 1604. For instance, a bottom-most row of the topneighboring block above the reference block 1604 can include the firstrow of samples 1646 and the additional row of samples 1647, which can belocated immediately above a top-most row of samples in the referenceblock 1604. In some cases, the first row of samples 1646 can be from afirst top neighboring block and the additional row of samples 1647 canbe from a second top neighboring block that is different from the firsttop neighboring block, in which case the first top neighboring block andthe second top neighboring block are adjacent to the reference block1604. For instance, a bottom-most row of the first top neighboring blockcan include the first row of samples 1646 and can be located immediatelyabove the top-most row of samples in the reference block 1604, and abottom-most row of the second top neighboring block can include theadditional row of samples 1647 and can be located immediately above thetop-most row of samples in the reference block 1604.

In some cases, the first column of samples 1648 and the additionalcolumn of samples 1649 can be from a same left neighboring block (orfrom multiple blocks) that is adjacent to the reference block 1604. Forexample, a right-most column of the left neighboring block to the leftof the reference block 1604 can include the first column of samples 1648and the additional column of samples 1649, which can be locatedimmediately to the left of a left-most column of samples in thereference block 1604. In some cases, the first column of samples 1648can be from a first left neighboring block and the additional column ofsamples 1649 can be from a second left neighboring block that isdifferent from the first left neighboring block, in which case the firstleft neighboring block and the second left neighboring block areadjacent to the reference block 1604. For instance, a right-most columnof the first left neighboring block can include the first column ofsamples 1648 and can be located immediately to the left of the left-mostcolumn of samples in the reference block 1604. In such cases, aright-most column of the second left neighboring block can include theadditional column of samples 1649 and can be located immediately to theleft of the left-most column of samples in the reference block 1604.

In some examples, the coding device can also determine to use theadditional row of samples 1643 that are adjacent to the second VPDU 1632and the additional column of samples 1645 that are adjacent to the thirdVPDU 1634 for determining the IC parameters for the current block 1602.In some cases, the first row of samples 1642 and the additional row ofsamples 1643 can be from a same top neighboring block (or multiple topneighboring blocks) that is adjacent to the first VPDU 1630 and thesecond VPDU 1632. For instance, a bottom-most row of the top neighboringblock above the first VPDU 1630 and the second VPDU 1632 can include thefirst row of samples 1642 and the additional row of samples 1643, whichcan be located immediately above a top-most row of samples in thecurrent block 1602. In some cases, the first row of samples 1642 can befrom a first top neighboring block and the additional row of samples1643 can be from a second top neighboring block that is different fromthe first top neighboring block, where the first top neighboring blockis adjacent to the first VPDU 1630 and the second top neighboring blockis adjacent to the second VPDU 1632. For example, a bottom-most row ofthe first top neighboring block above the first VPDU 1630 can includethe first row of samples 1642 and can be located immediately above thetop-most row of samples in the current block 1602. In such cases, abottom-most row of the second top neighboring block above the secondVPDU 1632 can include the additional row of samples 1643 and can belocated immediately above the top-most row of samples in the currentblock 1602.

In some cases, the first column of samples 1644 and the additionalcolumn of samples 1645 can be from a same left neighboring block (orfrom multiple blocks) that is adjacent to the first VPDU 1630 and thethird VPDU 1634. For example, a right-most column of the leftneighboring block to the left of the current block 1602 can include thefirst column of samples 1644 and the additional column of samples 1645,which can be located immediately to the left of a left-most column ofsamples in the current block 1602. In some cases, the first column ofsamples 1644 can be from a first left neighboring block and theadditional column of samples 1645 can be from a second left neighboringblock that is different from the first left neighboring block, where thefirst left neighboring block and the second left neighboring block areadjacent to the current block 1602. For instance, a right-most column ofthe first left neighboring block can include the first column of samples1644 and can be located immediately to the left of the left-most columnof samples in the current block 1602. A right-most column of the secondleft neighboring block can include the additional column of samples 1645and can be located immediately to the left of the left-most column ofsamples in the current block 1602.

The first row of samples 1642 and the first column of samples 1644neighboring the first VPDU 1630, the additional row of samples 1643neighboring the second VPDU 1632, and the additional column of samples1645 neighboring the third VPDU 1634 can be used as Rec_(neig) inEquations (2) and (3) above, and the first row of samples 1646, theadditional row of samples 1647, the first column of samples 1648, andthe additional column of samples 1649 neighboring the reference block1604 can be used as Rec_(refneig) in Equations (2) and (3) above, and/orcan be used by any other IC parameter derivation technique (e.g., thatproposed in JEM) to determine the IC parameters for the first VPDU 1630.Similar to that described above, the first VPDU 1630 can share thecalculated IC parameter with the second VPDU 1632, the third VPDU 1634,and the fourth VPDU 1636 in the current block 1602.

Similar to that described above, the MC access memory 1610 area of thefirst VPDU 1630 includes the first row of samples 1646, the additionalrow of samples 1647, the first column of samples 1648, and theadditional column of samples 1649 neighboring the reference block 1604.Because such samples are in the MC access memory 1610 area, there is noadditional impact to the memory bandwidth when IC is performed usingthese samples, and the additional samples 1643, 1645, 1647, and 1649 canbe used to determine IC parameters for the current block 1602 withoutany increase in the number of VPDU pipeline stage cycles and with bettercoding performance of IC (e.g., as compared to the number of VPDUpipeline stage cycles used and the IC performance achieved by using theJVET-M0088 technique) because more samples are used to derive the ICparameters.

A coding device can determine to use any sub-combination of the samplesshown in FIG. 16 for determining IC parameters for the current block1602. For example, while the example of FIG. 16 is shown to include thefirst row of samples 1642, the additional row of samples 1643, the firstcolumn of samples 1644, and the additional column of samples 1645neighboring the first VPDU 1630, the second VPDU 1632, and the thirdVPDU 1634, respectively, and to include the first row of samples 1646,the additional row of samples 1647, the first column of samples 1648,and the additional column of samples 1649 neighboring the referenceblock 1604, the coding device can use any sub-combination of thesesamples for determining IC parameters for the current block 1602. In oneexample, the coding device can determine to use the first row of samples1642, the additional row of samples 1643, and the first column ofsamples 1644 for determining IC parameters for the current block 1602.In another example, the coding device can determine to use the first rowof samples 1642, the first column of samples 1644, and the additionalcolumn of samples 1645 for determining IC parameters for the currentblock 1602. In yet another example, the first row of samples 1646, theadditional row of samples 1647, and the first column of samples 1648 canbe used by the coding device to determine IC parameters for the currentblock 1602. In another example, the coding device can determine to usethe first row of samples 1646, the first column of samples 1648, and theadditional column of samples 1649 neighboring the reference block 1604for determining IC parameters for the current block 1602. In anotherexample, the coding device can determine to use, for determining ICparameters for the current block 1602, the first row of samples 1642 andthe first column of samples 1644 neighboring the first VPDU 1630, theadditional row of samples 1643 neighboring the second VPDU 1632, and theadditional column of samples 1645 neighboring the third VPDU 1634, andthe first row of samples 1646 and the first column of samples 1648neighboring the reference block 1604. In another example, the codingdevice can determine to use the first row of samples 1642 and the firstcolumn of samples 1644 neighboring the first VPDU 1630, and the firstrow of samples 1646, the additional row of samples 1647, the firstcolumn of samples 1648, and the additional column of samples 1649neighboring the reference block 1604 for determining IC parameters forthe current block 1602.

It will be appreciated that other combinations of the first row ofsamples 1642 and the first column of samples 1644 neighboring the firstVPDU 1630, the first row of samples 1646 and the first column of samples1648 neighboring the reference block 1604, and any of the additionalsamples (e.g., the additional row of samples 1643 neighboring the secondVPDU 1632, the additional column of samples 1645 neighboring the thirdVPDU 1634, the additional row of samples 1647 neighboring the referenceblock 1604, and/or the additional column of samples 1649 neighboring thereference block 1604) can be used by a coding device to determine ICparameters for the current block 1602.

FIG. 17 is a diagram illustrating another example of determining ICparameters for a current block 1702 using additional samples. Theexample in FIG. 17 is similar to that in FIG. 16, with additional rowsand columns being used in addition to those used in the example of FIG.16. For example, in addition to the first row of samples 1742, the firstcolumn of samples 1744, the additional row of samples 1743, and theadditional column of samples 1745, an additional row of samples 1750neighboring the second VPDU 1732 and an additional column of samples1751 neighboring the third VPDU 1734 are used to determine the ICparameters for the current block 1702. Further, in addition to the firstrow of samples 1746, the first column of samples 1748, the additionalrow of samples 1747, and the additional column of samples 1749, anadditional row of samples 1752 and an additional column of samples 1753neighboring the reference block 1704 of the first VPDU 1730 are used todetermine the IC parameters for the current block 1702. The referenceblock 1704 can be determined using the motion vector 1705.

Because the MC access memory 1710 area of the first VPDU 1730 includesthe first row of samples 1746, the additional row of samples 1747, theadditional row of samples 1752, the first column of samples 1748, theadditional column of samples 1749, and the additional column of samples1753 neighboring the reference block 1704, no additional impact to thememory bandwidth is present when IC is performed using these samples.The additional samples 1743, 1745, 1750, 1751, 1747, 1749, 1752, and1753 can be used to determine IC parameters for the current block 1702without any increase in the number of VPDU pipeline stage cycles andwith better IC coding performance than that achieved by using theJVET-M0088 technique, because more samples are used to derive the ICparameters.

It will be appreciated that any combinations of the first row of samples1742, the first column of samples 1744, the first row of samples 1746,the first column of samples 1748, and any of the additional samples(e.g., the additional samples 1743, 1745, 1750, 1751, 1747, 1749, 1752,and 1753) can be used by a coding device to determine IC parameters forthe current block 1702.

As noted above, when a block contains multiple VPDUs, the LIC parametersdetermined for one VPDU of the multiple VPDUs can be shared among theother VPDUs, in which case IC parameters for only one of the VPDUs needsto be determined. In some examples, if a block contains multiple VPDUs,IC parameters can be derived for each VPDU separately. For example,referring to FIG. 15, the IC parameters for the first VPDU 1530 can bedetermined using the first row of samples 1542 and the first column ofsamples 1544 neighboring the first VPDU 1530, using the first row ofsamples 1546 and the second row of samples 1547 from the top neighboringblock (or from multiple top neighboring blocks) that is adjacent to thereference block 1504, and using the first column of samples 1548 and thesecond column of samples 1549 from the left neighboring block (or frommultiple left neighboring blocks) that is adjacent to the referenceblock 1504, as described above. The IC parameters for the second VPDU1532 can be determined using the second row of samples 1543 andcorresponding samples neighboring a reference block (not shown) for thesecond VPDU 1532. The IC parameters for the third VPDU 1534 can bedetermined using the second column of samples 1545 and correspondingsamples neighboring a reference block (not shown) for the third VPDU1534. The IC parameters for the fourth VPDU 1536 can be set to a defaultvalue (e.g., scaling factor a=1 and/or offset b=1), or the IC parametersfrom one or more of the first VPDU 1530, the second VPDU 1532, or thethird VPDU 1534 can be shared with the fourth VPDU 1536.

FIG. 18 is a flowchart illustrating an example of a process 1800 ofprocessing video data using the techniques described herein. At block1802, the process 1800 includes obtaining a current block of a pictureof the video data.

At block 1804, the process 1800 includes determining the current blockincludes more than one virtual pipeline data unit (VPDU). For instance,the process 1800 can include determining a size of a VPDU, determiningone or more of a width or a height of the current block, determining oneor more of the width or the height of the current block is larger thanthe size of the VPDU, and determining the current block includes morethan one VPDU based on determining one or more of the width or theheight of the current block is larger than the size of the VPDU. In oneillustrative example, the size of the VPDU can be 64×64 (with a width of64 samples and a height of 64 samples). The block can include a size of128×128 (with a width of 128 samples and a height of 128 samples). Insuch an example, the block can include four VPDUs, such as the block1002 shown in the example of FIG. 10.

At block 1806, the process 1800 includes obtaining, for illuminationcompensation, current neighbor samples for the current block. Thecurrent neighbor samples include samples from a first row of samplesfrom a first neighboring block of a first VPDU included in the currentblock, samples from a first column of samples from a second neighboringblock of the first VPDU, or both the samples from the first row ofsamples from the first neighboring block and the samples from the firstcolumn of samples from the second neighboring block. In someimplementations, the first neighboring block of the first VPDU includesa top neighboring block and the second neighboring block of the firstVPDU includes a left neighboring block. In one illustrative example, thecurrent neighbor samples can include the first row of samples 1442and/or the first column of samples 1444 shown in FIG. 14.

At block 1808, the process 1800 includes obtaining, for illuminationcompensation, reference neighbor samples for the current block. Thereference neighbor samples include samples from a first row of samplesfrom a first neighboring block of a reference block, samples from afirst column of samples from a second neighboring block of the referenceblock, or both the samples from the first row of samples from the firstneighboring block and the samples from the first column of samples froma second neighboring block of the reference block. In someimplementations, the first neighboring block of the reference blockincludes a top neighboring block and the second neighboring block of thereference block includes a left neighboring block. In one illustrativeexample, the current neighbor samples can include the first row ofsamples 1446 and/or the first column of samples 1448 shown in FIG. 14.

At block 1810, the process 1800 includes obtaining, for illuminationcompensation, additional neighbor samples for the current block. Theadditional neighbor samples can include additional samples other thanthe current neighbor samples for the current block and the referenceneighbor samples for the current block. For instance, the additionalsamples can include a second row of samples from the first neighboringblock of the first VPDU, a second column of samples from the secondneighboring block of the first VPDU, a second row of samples from thefirst neighboring block of the reference block, a second column ofsamples from the second neighboring block of the reference block,samples from a neighboring block of a second VPDU included in thecurrent block, or any combination thereof.

In one illustrative example, the additional neighbor samples includesamples from the second row of samples from the first neighboring blockof the first VPDU and samples from the second column of samples from thesecond neighboring block of the first VPDU. For instance, referring toFIG. 14 as an illustrative example, the additional neighbor samples caninclude the second row of samples 1443 from the top neighboring blockadjacent to the first VPDU 1430 and the second column of samples 1445from the left neighboring block that is adjacent to the first VPDU 1430.In some cases, the second row of samples from the first neighboringblock of the first VPDU includes at least two rows of samples (e.g., thesecond row of samples 1443 and at least one other row of samples),and/or the second column of samples from the second neighboring block ofthe first VPDU includes at least two columns of samples (e.g., thesecond column of samples 1445 and at least one other column of samples).

In another illustrative example, the additional neighbor samples includesamples from the second row of samples from the first neighboring blockof the first VPDU, samples from second column of samples from the secondneighboring block of the first VPDU, samples from the second row ofsamples from the first neighboring block of the reference block, andsamples from the second column of samples from the second neighboringblock of the reference block. For instance, again referring to FIG. 14as an illustrative example, the additional neighbor samples can includethe second row of samples 1443 from the top neighboring block adjacentto the first VPDU 1430, the second column of samples 1445 from the leftneighboring block that is adjacent to the first VPDU 1430, the secondrow of samples 1447 from the top neighboring block adjacent to thereference block 1404, and second column of samples 1449 from the leftneighboring block adjacent to the reference block 1404. In some cases,the second row of samples from the first neighboring block of the firstVPDU includes at least two rows of samples, the second column of samplesfrom the second neighboring block of the first VPDU includes at leasttwo columns of samples, the second row of samples from the firstneighboring block of the reference block includes at least two rows ofsamples, and/or the second column of samples from the second neighboringblock of the reference block includes at least two columns of samples.

In another illustrative example, the additional neighbor samples includethe samples from the neighboring block of the second VPDU included inthe current block. In some cases, the additional neighbor samplesinclude samples from a neighboring block of a third VPDU included in thecurrent block. In some cases, the samples from the neighboring block ofthe second VPDU include a row of samples from the neighboring block ofthe second VPDU, and the samples from the neighboring block of the thirdVPDU include a column of samples from the neighboring block of the thirdVPDU. For example, referring to FIG. 15, the samples from theneighboring block of the second VPDU include the second row of samples1543, and the samples from the neighboring block of the third VPDUinclude the second column of samples 1545. In some examples, the row ofsamples from the first neighboring block of the second VPDU includes atleast two rows of samples, and the column of samples from theneighboring block of the third VPDU includes at least two columns ofsamples.

In another illustrative example, the additional neighbor samples includethe samples from the neighboring block of the second VPDU, samples fromthe second row of samples from the first neighboring block of thereference block, and samples from the second column of samples from thesecond neighboring block of the reference block. In some cases, thesamples from the neighboring block of the second VPDU include a row ofsamples from the neighboring block of the second VPDU and a column ofsamples from a neighboring block of a third VPDU. For example, referringto FIG. 15, the additional samples can include the second row of samples1543 neighboring the second VPDU 1532, the second column of samples 1545neighboring the third VPDU 1534, the second row of samples 1547neighboring the reference block 1504, and the second column of samples1549 neighboring the reference block 1504.

In another example, the additional neighbor samples include one or moreof samples to a right of a top neighboring row of the current block,samples below a left neighboring column of the current block, samples toa right of a top neighboring row of the reference block, and/or samplesbelow a left neighboring column of the reference block. For instance,referring to FIG. 16 as an illustrative example, the samples to theright of the top neighboring row of the current block include theadditional row of samples 1643 to the right of the first VPDU 1630, thesamples below the left neighboring column of the current block includethe additional column of samples 1645 below the first VPDU 1630, thesamples to the right of the top neighboring row of the reference blockinclude the additional row of samples 1647 to the right of the referenceblock 1604, and the samples below the left neighboring column of thereference block include the additional column samples 1649 below thereference block 1604.

At block 1812, the process 1800 includes determining one or moreillumination compensation parameters for the current block using thecurrent neighbor samples, the reference neighbor samples, and theadditional neighbor samples. The additional neighbor samples are usedfor determining the one or more illumination compensation parametersbased on the current block covering more than one VPDU. For example, asnoted above, when a block includes more than one VPDU, such as theexample illustrated in FIG. 10, neighboring samples used for ICparameter calculation for the block (e.g., for calculating one or moreoffsets b and/or one or more weights or scaling factors a) lead to theneed for additional memory access and to increased bandwidth usage. Theadditional neighbor samples can be determined in such a way that thereis no need for additional memory access or increased bandwidth usage(e.g., such that the MC access memory for a given VPDU, such as thereference block 1604 for the first VPDU 1630, is needed for encodingand/or decoding the block).

At block 1814, the process 1800 includes performing illuminationcompensation for the current block of the picture using the one or moreillumination compensation parameters. The one or more illuminationcompensation parameters include at least one scaling factor and at leastone offset. As described above, determining the one or more illuminationcompensation parameters for the current block can include minimizing adifference between samples from one or more neighboring blocks of thecurrent block and samples from one or more neighboring blocks of areference block of the current block. For instance, determining the oneor more illumination compensation parameters for the current block caninclude minimizing a difference between the samples from the first rowof samples from the first neighboring block of the first VPDU and/or thesamples from the first column of samples from the second neighboringblock of the first VPDU, and the samples from the first row of samplesfrom the first neighboring block of the reference block and/or thesamples from the first column of samples from the second neighboringblock of the reference block.

In some examples, as described above, subsampling is not applied tosamples from the first neighboring block of the first VPDU, samples fromthe second neighboring block of the first VPDU, samples from the firstneighboring block of the reference block, and samples from the secondneighboring block of the reference block when performing illuminationcompensation for the current block.

In some examples, the process 1800 can include decoding the currentblock of video data based on performing the illumination compensationfor the current block. For instance, the process 1800 can includedetermining a residual value for the current block, performing aprediction mode for the current block, and reconstructing at least onesample of the current block based on the illumination compensationperformed for the current block, the residual value for the currentblock, and the prediction mode performed for the current block.

In some examples, the process 1800 can include generating an encodedvideo bitstream. The encoded video bitstream can include at least aportion of the current block of video data. In some examples, theprocess 1800 can include signaling the encoded video bitstream. In somecases, the process 1800 can include signaling the one or moreillumination compensation parameters in the encoded video bitstream.

In some implementations, the processes described herein (includingprocess 1800) can be performed by a computing device or an apparatus,such as the system 100 shown in FIG. 1. For example, the processes canbe performed by the encoding device 104 shown in FIG. 1 and FIG. 19, byanother video source-side device or video transmission device, by thedecoding device 112 shown in FIG. 1 and FIG. 20, and/or by anotherclient-side device, such as a player device, a display, or any otherclient-side device. In some cases, the computing device or apparatus mayinclude one or more input devices, one or more output devices, one ormore processors, one or more microprocessors, one or moremicrocomputers, and/or other component(s) that is/are configured tocarry out the steps of process 1800. In some examples, the computingdevice may include a mobile device, a desktop computer, a servercomputer and/or server system, or other type of computing device. Insome examples, the computing device or apparatus may include a cameraconfigured to capture video data (e.g., a video sequence) includingvideo frames. In some examples, a camera or other capture device thatcaptures the video data is separate from the computing device, in whichcase the computing device receives or obtains the captured video data.The computing device may include a network interface configured tocommunicate the video data. The network interface may be configured tocommunicate Internet Protocol (IP) based data or other type of data. Insome examples, the computing device or apparatus may include a displayfor displaying output video content, such as samples of pictures of avideo bitstream.

The components of the computing device (e.g., the one or more inputdevices, one or more output devices, one or more processors, one or moremicroprocessors, one or more microcomputers, and/or other component) canbe implemented in circuitry. For example, the components can includeand/or can be implemented using electronic circuits or other electronichardware, which can include one or more programmable electronic circuits(e.g., microprocessors, graphics processing units (GPUs), digital signalprocessors (DSPs), central processing units (CPUs), and/or othersuitable electronic circuits), and/or can include and/or be implementedusing computer software, firmware, or any combination thereof, toperform the various operations described herein.

The processes described herein (including process 1800) can be describedwith respect to logical flow diagrams, the operation of which representa sequence of operations that can be implemented in hardware, computerinstructions, or a combination thereof. In the context of computerinstructions, the operations represent computer-executable instructionsstored on one or more computer-readable storage media that, whenexecuted by one or more processors, perform the recited operations.Generally, computer-executable instructions include routines, programs,objects, components, data structures, and the like that performparticular functions or implement particular data types. The order inwhich the operations are described is not intended to be construed as alimitation, and any number of the described operations can be combinedin any order and/or in parallel to implement the processes.

Additionally, the processes described herein (including process 1800)may be performed under the control of one or more computer systemsconfigured with executable instructions and may be implemented as code(e.g., executable instructions, one or more computer programs, or one ormore applications) executing collectively on one or more processors, byhardware, or combinations thereof: As noted above, the code may bestored on a computer-readable or machine-readable storage medium, forexample, in the form of a computer program comprising a plurality ofinstructions executable by one or more processors. The computer-readableor machine-readable storage medium may be non-transitory.

The coding techniques discussed herein may be implemented in an examplevideo encoding and decoding system (e.g., system 100). In some examples,a system includes a source device that provides encoded video data to bedecoded at a later time by a destination device. In particular, thesource device provides the video data to destination device via acomputer-readable medium. The source device and the destination devicemay comprise any of a wide range of devices, including desktopcomputers, notebook (i.e., laptop) computers, tablet computers, set-topboxes, telephone handsets such as so-called “smart” phones, so-called“smart” pads, televisions, cameras, display devices, digital mediaplayers, video gaming consoles, video streaming device, or the like. Insome cases, the source device and the destination device may be equippedfor wireless communication.

The destination device may receive the encoded video data to be decodedvia the computer-readable medium. The computer-readable medium maycomprise any type of medium or device capable of moving the encodedvideo data from source device to destination device. In one example,computer-readable medium may comprise a communication medium to enablesource device to transmit encoded video data directly to destinationdevice in real-time. The encoded video data may be modulated accordingto a communication standard, such as a wireless communication protocol,and transmitted to destination device. The communication medium maycomprise any wireless or wired communication medium, such as a radiofrequency (RF) spectrum or one or more physical transmission lines. Thecommunication medium may form part of a packet-based network, such as alocal area network, a wide-area network, or a global network such as theInternet. The communication medium may include routers, switches, basestations, or any other equipment that may be useful to facilitatecommunication from source device to destination device.

In some examples, encoded data may be output from output interface to astorage device. Similarly, encoded data may be accessed from the storagedevice by input interface. The storage device may include any of avariety of distributed or locally accessed data storage media such as ahard drive, Blu-ray discs, DVDs. CD-ROMs, flash memory, volatile ornon-volatile memory, or any other suitable digital storage media forstoring encoded video data. In a further example, the storage device maycorrespond to a file server or another intermediate storage device thatmay store the encoded video generated by source device. Destinationdevice may access stored video data from the storage device viastreaming or download. The file server may be any type of server capableof storing encoded video data and transmitting that encoded video datato the destination device. Example file servers include a web server(e.g., for a website), an FTP server, network attached storage (NAS)devices, or a local disk drive. Destination device may access theencoded video data through any standard data connection, including anInternet connection. This may include a wireless channel (e.g., a Wi-Ficonnection), a wired connection (e.g., DSL, cable modem, etc.), or acombination of both that is suitable for accessing encoded video datastored on a file server. The transmission of encoded video data from thestorage device may be a streaming transmission, a download transmission,or a combination thereof.

The techniques of this disclosure are not necessarily limited towireless applications or settings. The techniques may be applied tovideo coding in support of any of a variety of multimedia applications,such as over-the-air television broadcasts, cable televisiontransmissions, satellite television transmissions, Internet streamingvideo transmissions, such as dynamic adaptive streaming over HTTP(DASH), digital video that is encoded onto a data storage medium,decoding of digital video stored on a data storage medium, or otherapplications. In some examples, system may be configured to supportone-way or two-way video transmission to support applications such asvideo streaming, video playback, video broadcasting, and/or videotelephony.

In one example the source device includes a video source, a videoencoder, and a output interface. The destination device may include aninput interface, a video decoder, and a display device. The videoencoder of source device may be configured to apply the techniquesdisclosed herein. In other examples, a source device and a destinationdevice may include other components or arrangements. For example, thesource device may receive video data from an external video source, suchas an external camera. Likewise, the destination device may interfacewith an external display device, rather than including an integrateddisplay device.

The example system above is merely one example. Techniques forprocessing video data in parallel may be performed by any digital videoencoding and/or decoding device. Although generally the techniques ofthis disclosure are performed by a video encoding device, the techniquesmay also be performed by a video encoder/decoder, typically referred toas a “CODEC.” Moreover, the techniques of this disclosure may also beperformed by a video preprocessor. Source device and destination deviceare merely examples of such coding devices in which source devicegenerates coded video data for transmission to destination device. Insome examples, the source and destination devices may operate in asubstantially symmetrical manner such that each of the devices includevideo encoding and decoding components. Hence, example systems maysupport one-way or two-way video transmission between video devices,e.g., for video streaming, video playback, video broadcasting, or videotelephony.

The video source may include a video capture device, such as a videocamera, a video archive containing previously captured video, and/or avideo feed interface to receive video from a video content provider. Asa further alternative, the video source may generate computergraphics-based data as the source video, or a combination of live video,archived video, and computer-generated video. In some cases, if videosource is a video camera, source device and destination device may formso-called camera phones or video phones. As mentioned above, however,the techniques described in this disclosure may be applicable to videocoding in general, and may be applied to wireless and/or wiredapplications. In each case, the captured, pre-captured, orcomputer-generated video may be encoded by the video encoder. Theencoded video information may then be output by output interface ontothe computer-readable medium.

As noted the computer-readable medium may include transient media, suchas a wireless broadcast or wired network transmission, or storage media(that is, non-transitory storage media), such as a hard disk, flashdrive, compact disc, digital video disc, Blu-ray disc, or othercomputer-readable media. In some examples, a network server (not shown)may receive encoded video data from the source device and provide theencoded video data to the destination device, e.g., via networktransmission. Similarly, a computing device of a medium productionfacility, such as a disc stamping facility, may receive encoded videodata from the source device and produce a disc containing the encodedvideo data. Therefore, the computer-readable medium may be understood toinclude one or more computer-readable media of various forms, in variousexamples.

The input interface of the destination device receives information fromthe computer-readable medium. The information of the computer-readablemedium may include syntax information defined by the video encoder,which is also used by the video decoder, that includes syntax elementsthat describe characteristics and/or processing of blocks and othercoded units, e.g., group of pictures (GOP). A display device displaysthe decoded video data to a user, and may comprise any of a variety ofdisplay devices such as a cathode ray tube (CRT), a liquid crystaldisplay (LCD), a plasma display, an organic light emitting diode (OLED)display, or another type of display device. Various embodiments of theapplication have been described.

Specific details of the encoding device 104 and the decoding device 112are shown in FIG. 11 and FIG. 12, respectively. FIG. 11 is a blockdiagram illustrating an example encoding device 104 that may implementone or more of the techniques described in this disclosure. Encodingdevice 104 may, for example, generate the syntax structures describedherein (e.g., the syntax structures of a VPS, SPS, PPS, or other syntaxelements). Encoding device 104 may perform intra-prediction andinter-prediction coding of video blocks within video slices. Aspreviously described, intra-coding relies, at least in part, on spatialprediction to reduce or remove spatial redundancy within a given videoframe or picture. Inter-coding relies, at least in part, on temporalprediction to reduce or remove temporal redundancy within adjacent orsurrounding frames of a video sequence. Intra-mode (I mode) may refer toany of several spatial based compression modes. Inter-modes, such asuni-directional prediction (P mode) or bi-prediction (B mode), may referto any of several temporal-based compression modes.

The encoding device 104 includes a partitioning unit 35, predictionprocessing unit 41, filter unit 63, picture memory 64, summer 50,transform processing unit 52, quantization unit 54, and entropy encodingunit 56. Prediction processing unit 41 includes motion estimation unit42, motion compensation unit 44, and intra-prediction processing unit46. For video block reconstruction, encoding device 104 also includesinverse quantization unit 58, inverse transform processing unit 60, andsummer 62. Filter unit 63 is intended to represent one or more loopfilters such as a deblocking filter, an adaptive loop filter (ALF), anda sample adaptive offset (SAO) filter. Although filter unit 63 is shownin FIG. 11 as being an in loop filter, in other configurations, filterunit 63 may be implemented as a post loop filter. A post processingdevice 57 may perform additional processing on encoded video datagenerated by the encoding device 104. The techniques of this disclosuremay in some instances be implemented by the encoding device 104. Inother instances, however, one or more of the techniques of thisdisclosure may be implemented by post processing device 57.

As shown in FIG. 11, the encoding device 104 receives video data, andpartitioning unit 35 partitions the data into video blocks. Thepartitioning may also include partitioning into slices, slice segments,tiles, or other larger units, as wells as video block partitioning,e.g., according to a quadtree structure of LCUs and CUs. The encodingdevice 104 generally illustrates the components that encode video blockswithin a video slice to be encoded. The slice may be divided intomultiple video blocks (and possibly into sets of video blocks referredto as tiles). Prediction processing unit 41 may select one of aplurality of possible coding modes, such as one of a plurality ofintra-prediction coding modes or one of a plurality of inter-predictioncoding modes, for the current video block based on error results (e.g.,coding rate and the level of distortion, or the like). Predictionprocessing unit 41 may provide the resulting intra- or inter-coded blockto summer 50 to generate residual block data and to summer 62 toreconstruct the encoded block for use as a reference picture.

Intra-prediction processing unit 46 within prediction processing unit 41may perform intra-prediction coding of the current video block relativeto one or more neighboring blocks in the same frame or slice as thecurrent block to be coded to provide spatial compression. Motionestimation unit 42 and motion compensation unit 44 within predictionprocessing unit 41 perform inter-predictive coding of the current videoblock relative to one or more predictive blocks in one or more referencepictures to provide temporal compression.

Motion estimation unit 42 may be configured to determine theinter-prediction mode for a video slice according to a predeterminedpattern for a video sequence. The predetermined pattern may designatevideo slices in the sequence as P slices, B slices, or GPB slices.Motion estimation unit 42 and motion compensation unit 44 may be highlyintegrated, but are illustrated separately for conceptual purposes.Motion estimation, performed by motion estimation unit 42, is theprocess of generating motion vectors, which estimate motion for videoblocks. A motion vector, for example, may indicate the displacement of aprediction unit (PU) of a video block within a current video frame orpicture relative to a predictive block within a reference picture.

A predictive block is a block that is found to closely match the PU ofthe video block to be coded in terms of pixel difference, which may bedetermined by sum of absolute difference (SAD), sum of square difference(SSD), or other difference metrics. In some examples, the encodingdevice 104 may calculate values for sub-integer pixel positions ofreference pictures stored in picture memory 64. For example, theencoding device 104 may interpolate values of one-quarter pixelpositions, one-eighth pixel positions, or other fractional pixelpositions of the reference picture. Therefore, motion estimation unit 42may perform a motion search relative to the full pixel positions andfractional pixel positions and output a motion vector with fractionalpixel precision.

Motion estimation unit 42 calculates a motion vector for a PU of a videoblock in an inter-coded slice by comparing the position of the PU to theposition of a predictive block of a reference picture. The referencepicture may be selected from a first reference picture list (List 0) ora second reference picture list (List 1), each of which identify one ormore reference pictures stored in picture memory 64. Motion estimationunit 42 sends the calculated motion vector to entropy encoding unit 56and motion compensation unit 44.

Motion compensation, performed by motion compensation unit 44, mayinvolve fetching or generating the predictive block based on the motionvector determined by motion estimation, possibly performinginterpolations to sub-pixel precision. Upon receiving the motion vectorfor the PU of the current video block, motion compensation unit 44 maylocate the predictive block to which the motion vector points in areference picture list. The encoding device 104 forms a residual videoblock by subtracting pixel values of the predictive block from the pixelvalues of the current video block being coded, forming pixel differencevalues. The pixel difference values form residual data for the block,and may include both luma and chroma difference components. Summer 50represents the component or components that perform this subtractionoperation. Motion compensation unit 44 may also generate syntax elementsassociated with the video blocks and the video slice for use by thedecoding device 112 in decoding the video blocks of the video slice.

Intra-prediction processing unit 46 may intra-predict a current block,as an alternative to the inter-prediction performed by motion estimationunit 42 and motion compensation unit 44, as described above. Inparticular, intra-prediction processing unit 46 may determine anintra-prediction mode to use to encode a current block. In someexamples, intra-prediction processing unit 46 may encode a current blockusing various intra-prediction modes, e.g., during separate encodingpasses, and intra-prediction unit processing 46 may select anappropriate intra-prediction mode to use from the tested modes. Forexample, intra-prediction processing unit 46 may calculaterate-distortion values using a rate-distortion analysis for the varioustested intra-prediction modes, and may select the intra-prediction modehaving the best rate-distortion characteristics among the tested modes.Rate-distortion analysis generally determines an amount of distortion(or error) between an encoded block and an original, unencoded blockthat was encoded to produce the encoded block, as well as a bit rate(that is, a number of bits) used to produce the encoded block.Intra-prediction processing unit 46 may calculate ratios from thedistortions and rates for the various encoded blocks to determine whichintra-prediction mode exhibits the best rate-distortion value for theblock.

In any case, after selecting an intra-prediction mode for a block,intra-prediction processing unit 46 may provide information indicativeof the selected intra-prediction mode for the block to entropy encodingunit 56. Entropy encoding unit 56 may encode the information indicatingthe selected intra-prediction mode. The encoding device 104 may includein the transmitted bitstream configuration data definitions of encodingcontexts for various blocks as well as indications of a most probableintra-prediction mode, an intra-prediction mode index table, and amodified intra-prediction mode index table to use for each of thecontexts. The bitstream configuration data may include a plurality ofintra-prediction mode index tables and a plurality of modifiedintra-prediction mode index tables (also referred to as codeword mappingtables).

After prediction processing unit 41 generates the predictive block forthe current video block via either inter-prediction or intra-prediction,the encoding device 104 forms a residual video block by subtracting thepredictive block from the current video block. The residual video datain the residual block may be included in one or more TUs and applied totransform processing unit 52. Transform processing unit 52 transformsthe residual video data into residual transform coefficients using atransform, such as a discrete cosine transform (DCT) or a conceptuallysimilar transform. Transform processing unit 52 may convert the residualvideo data from a pixel domain to a transform domain, such as afrequency domain.

Transform processing unit 52 may send the resulting transformcoefficients to quantization unit 54. Quantization unit 54 quantizes thetransform coefficients to further reduce bit rate. The quantizationprocess may reduce the bit depth associated with some or all of thecoefficients. The degree of quantization may be modified by adjusting aquantization parameter. In some examples, quantization unit 54 may thenperform a scan of the matrix including the quantized transformcoefficients. Alternatively, entropy encoding unit 56 may perform thescan.

Following quantization, entropy encoding unit 56 entropy encodes thequantized transform coefficients. For example, entropy encoding unit 56may perform context adaptive variable length coding (CAVLC), contextadaptive binary arithmetic coding (CABAC), syntax-based context-adaptivebinary arithmetic coding (SBAC), probability interval partitioningentropy (PIPE) coding or another entropy encoding technique. Followingthe entropy encoding by entropy encoding unit 56, the encoded bitstreammay be transmitted to the decoding device 112, or archived for latertransmission or retrieval by the decoding device 112. Entropy encodingunit 56 may also entropy encode the motion vectors and the other syntaxelements for the current video slice being coded.

Inverse quantization unit 58 and inverse transform processing unit 60apply inverse quantization and inverse transformation, respectively, toreconstruct the residual block in the pixel domain for later use as areference block of a reference picture. Motion compensation unit 44 maycalculate a reference block by adding the residual block to a predictiveblock of one of the reference pictures within a reference picture list.Motion compensation unit 44 may also apply one or more interpolationfilters to the reconstructed residual block to calculate sub-integerpixel values for use in motion estimation. Summer 62 adds thereconstructed residual block to the motion compensated prediction blockproduced by motion compensation unit 44 to produce a reference block forstorage in picture memory 64. The reference block may be used by motionestimation unit 42 and motion compensation unit 44 as a reference blockto inter-predict a block in a subsequent video frame or picture.

In this manner, the encoding device 104 of FIG. 11 represents an exampleof a video encoder configured to perform any of the techniques describedherein, including the process described above with respect to FIG. 18.In some cases, some of the techniques of this disclosure may also beimplemented by post processing device 57.

FIG. 12 is a block diagram illustrating an example decoding device 112.The decoding device 112 includes an entropy decoding unit 80, predictionprocessing unit 81, inverse quantization unit 86, inverse transformprocessing unit 88, summer 90, filter unit 91, and picture memory 92.Prediction processing unit 81 includes motion compensation unit 82 andintra prediction processing unit 84. The decoding device 112 may, insome examples, perform a decoding pass generally reciprocal to theencoding pass described with respect to the encoding device 104 fromFIG. 12.

During the decoding process, the decoding device 112 receives an encodedvideo bitstream that represents video blocks of an encoded video sliceand associated syntax elements sent by the encoding device 104. In someembodiments, the decoding device 112 may receive the encoded videobitstream from the encoding device 104. In some embodiments, thedecoding device 112 may receive the encoded video bitstream from anetwork entity 79, such as a server, a media-aware network element(MANE), a video editor/splicer, or other such device configured toimplement one or more of the techniques described above. Network entity79 may or may not include the encoding device 104. Some of thetechniques described in this disclosure may be implemented by networkentity 79 prior to network entity 79 transmitting the encoded videobitstream to the decoding device 112. In some video decoding systems,network entity 79 and the decoding device 112 may be parts of separatedevices, while in other instances, the functionality described withrespect to network entity 79 may be performed by the same device thatcomprises the decoding device 112.

The entropy decoding unit 80 of the decoding device 112 entropy decodesthe bitstream to generate quantized coefficients, motion vectors, andother syntax elements. Entropy decoding unit 80 forwards the motionvectors and other syntax elements to prediction processing unit 81. Thedecoding device 112 may receive the syntax elements at the video slicelevel and/or the video block level. Entropy decoding unit 80 may processand parse both fixed-length syntax elements and variable-length syntaxelements in or more parameter sets, such as a VPS, SPS, and PPS.

When the video slice is coded as an intra-coded (1) slice, intraprediction processing unit 84 of prediction processing unit 81 maygenerate prediction data for a video block of the current video slicebased on a signaled intra-prediction mode and data from previouslydecoded blocks of the current frame or picture. When the video frame iscoded as an inter-coded (i.e., B, P or GPB) slice, motion compensationunit 82 of prediction processing unit 81 produces predictive blocks fora video block of the current video slice based on the motion vectors andother syntax elements received from entropy decoding unit 80. Thepredictive blocks may be produced from one of the reference pictureswithin a reference picture list. The decoding device 112 may constructthe reference frame lists. List 0 and List 1, using default constructiontechniques based on reference pictures stored in picture memory 92.

Motion compensation unit 82 determines prediction information for avideo block of the current video slice by parsing the motion vectors andother syntax elements, and uses the prediction information to producethe predictive blocks for the current video block being decoded. Forexample, motion compensation unit 82 may use one or more syntax elementsin a parameter set to determine a prediction mode (e.g., intra- orinter-prediction) used to code the video blocks of the video slice, aninter-prediction slice type (e.g., B slice, P slice, or GPB slice),construction information for one or more reference picture lists for theslice, motion vectors for each inter-encoded video block of the slice,inter-prediction status for each inter-coded video block of the slice,and other information to decode the video blocks in the current videoslice.

Motion compensation unit 82 may also perform interpolation based oninterpolation filters. Motion compensation unit 82 may use interpolationfilters as used by the encoding device 104 during encoding of the videoblocks to calculate interpolated values for sub-integer pixels ofreference blocks. In this case, motion compensation unit 82 maydetermine the interpolation filters used by the encoding device 104 fromthe received syntax elements, and may use the interpolation filters toproduce predictive blocks.

Inverse quantization unit 86 inverse quantizes, or de-quantizes, thequantized transform coefficients provided in the bitstream and decodedby entropy decoding unit 80. The inverse quantization process mayinclude use of a quantization parameter calculated by the encodingdevice 104 for each video block in the video slice to determine a degreeof quantization and, likewise, a degree of inverse quantization thatshould be applied. Inverse transform processing unit 88 applies aninverse transform (e.g., an inverse DCT or other suitable inversetransform), an inverse integer transform, or a conceptually similarinverse transform process, to the transform coefficients in order toproduce residual blocks in the pixel domain.

After motion compensation unit 82 generates the predictive block for thecurrent video block based on the motion vectors and other syntaxelements, the decoding device 112 forms a decoded video block by summingthe residual blocks from inverse transform processing unit 88 with thecorresponding predictive blocks generated by motion compensation unit82. Summer 90 represents the component or components that perform thissummation operation. If desired, loop filters (either in the coding loopor after the coding loop) may also be used to smooth pixel transitions,or to otherwise improve the video quality. Filter unit 91 is intended torepresent one or more loop filters such as a deblocking filter, anadaptive loop filter (ALF), and a sample adaptive offset (SAO) filter.Although filter unit 91 is shown in FIG. 12 as being an in loop filter,in other configurations, filter unit 91 may be implemented as a postloop filter. The decoded video blocks in a given frame or picture arethen stored in picture memory 92, which stores reference pictures usedfor subsequent motion compensation. Picture memory 92 also storesdecoded video for later presentation on a display device, such as videodestination device 122 shown in FIG. 1.

In this manner, the decoding device 112 of FIG. 12 represents an exampleof a video decoder configured to perform any of the techniques describedherein, including the process described above with respect to FIG. 18.

As used herein, the term “computer-readable medium” includes, but is notlimited to, portable or non-portable storage devices, optical storagedevices, and various other mediums capable of storing, containing, orcarrying instruction(s) and/or data. A computer-readable medium mayinclude a non-transitory medium in which data can be stored and thatdoes not include carrier waves and/or transitory electronic signalspropagating wirelessly or over wired connections. Examples of anon-transitory medium may include, but are not limited to, a magneticdisk or tape, optical storage media such as compact disk (CD) or digitalversatile disk (DVD), flash memory, memory or memory devices. Acomputer-readable medium may have stored thereon code and/ormachine-executable instructions that may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a class, or any combination of instructions, datastructures, or program statements. A code segment may be coupled toanother code segment or a hardware circuit by passing and/or receivinginformation, data, arguments, parameters, or memory contents.Information, arguments, parameters, data. etc. may be passed, forwarded,or transmitted via any suitable means including memory sharing, messagepassing, token passing, network transmission, or the like.

In some embodiments the computer-readable storage devices, mediums, andmemories can include a cable or wireless signal containing a bit streamand the like. However, when mentioned, non-transitory computer-readablestorage media expressly exclude media such as energy, carrier signals,electromagnetic waves, and signals per se.

Specific details are provided in the description above to provide athorough understanding of the embodiments and examples provided herein.However, it will be understood by one of ordinary skill in the art thatthe embodiments may be practiced without these specific details. Forclarity of explanation, in some instances the present technology may bepresented as including individual functional blocks including functionalblocks comprising devices, device components, steps or routines in amethod embodied in software, or combinations of hardware and software.Additional components may be used other than those shown in the figuresand/or described herein. For example, circuits, systems, networks,processes, and other components may be shown as components in blockdiagram form in order not to obscure the embodiments in unnecessarydetail. In other instances, well-known circuits, processes, algorithms,structures, and techniques may be shown without unnecessary detail inorder to avoid obscuring the embodiments.

Individual embodiments may be described above as a process or methodwhich is depicted as a flowchart, a flow diagram, a data flow diagram, astructure diagram, or a block diagram. Although a flowchart may describethe operations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be re-arranged. A process is terminated when itsoperations are completed, but could have additional steps not includedin a figure. A process may correspond to a method, a function, aprocedure, a subroutine, a subprogram, etc. When a process correspondsto a function, its termination can correspond to a return of thefunction to the calling function or the main function.

Processes and methods according to the above-described examples can beimplemented using computer-executable instructions that are stored orotherwise available from computer-readable media. Such instructions caninclude, for example, instructions and data which cause or otherwiseconfigure a general purpose computer, special purpose computer, or aprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware,source code, etc. Examples of computer-readable media that may be usedto store instructions, information used, and/or information createdduring methods according to described examples include magnetic oroptical disks, flash memory, USB devices provided with non-volatilememory, networked storage devices, and so on.

Devices implementing processes and methods according to thesedisclosures can include hardware, software, firmware, middleware,microcode, hardware description languages, or any combination thereof,and can take any of a variety of form factors. When implemented insoftware, firmware, middleware, or microcode, the program code or codesegments to perform the necessary tasks (e.g., a computer-programproduct) may be stored in a computer-readable or machine-readablemedium. A processor(s) may perform the necessary tasks. Typical examplesof form factors include laptops, smart phones, mobile phones, tabletdevices or other small form factor personal computers, personal digitalassistants, rackmount devices, standalone devices, and so on.Functionality described herein also can be embodied in peripherals oradd-in cards. Such functionality can also be implemented on a circuitboard among different chips or different processes executing in a singledevice, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are example means for providing the functionsdescribed in the disclosure.

In the foregoing description, aspects of the application are describedwith reference to specific embodiments thereof, but those skilled in theart will recognize that the application is not limited thereto. Thus,while illustrative embodiments of the application have been described indetail herein, it is to be understood that the inventive concepts may beotherwise variously embodied and employed, and that the appended claimsare intended to be construed to include such variations, except aslimited by the prior art. Various features and aspects of theabove-described application may be used individually or jointly.Further, embodiments can be utilized in any number of environments andapplications beyond those described herein without departing from thebroader spirit and scope of the specification. The specification anddrawings are, accordingly, to be regarded as illustrative rather thanrestrictive. For the purposes of illustration, methods were described ina particular order. It should be appreciated that in alternateembodiments, the methods may be performed in a different order than thatdescribed.

One of ordinary skill will appreciate that the less than (“<”) andgreater than (“>”) symbols or terminology used herein can be replacedwith less than or equal to (“≤”) and greater than or equal to (“≥”)symbols, respectively, without departing from the scope of thisdescription.

Where components are described as being “configured to” perform certainoperations, such configuration can be accomplished, for example, bydesigning electronic circuits or other hardware to perform theoperation, by programming programmable electronic circuits (e.g.,microprocessors, or other suitable electronic circuits) to perform theoperation, or any combination thereof.

The phrase “coupled to” refers to any component that is physicallyconnected to another component either directly or indirectly, and/or anycomponent that is in communication with another component (e.g.,connected to the other component over a wired or wireless connection,and/or other suitable communication interface) either directly orindirectly.

Claim language or other language reciting “at least one of” a set and/or“one or more” of a set indicates that one member of the set or multiplemembers of the set (in any combination) satisfy the claim. For example,claim language reciting “at least one of A and B” means A, B, or A andB. In another example, claim language reciting “at least one of A, B,and C” means A, B, C, or A and B, or A and C, or B and C, or A and B andC. The language “at least one of” a set and/or “one or more” of a setdoes not limit the set to the items listed in the set. For example,claim language reciting “at least one of A and B” can mean A, B, or Aand B, and can additionally include items not listed in the set of A andB.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedherein may be implemented as electronic hardware, computer software,firmware, or combinations thereof. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, circuits, and steps have been describedabove generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present application.

The techniques described herein may also be implemented in electronichardware, computer software, firmware, or any combination thereof: Suchtechniques may be implemented in any of a variety of devices such asgeneral purposes computers, wireless communication device handsets, orintegrated circuit devices having multiple uses including application inwireless communication device handsets and other devices. Any featuresdescribed as modules or components may be implemented together in anintegrated logic device or separately as discrete but interoperablelogic devices. If implemented in software, the techniques may berealized at least in part by a computer-readable data storage mediumcomprising program code including instructions that, when executed,performs one or more of the methods described above. Thecomputer-readable data storage medium may form part of a computerprogram product, which may include packaging materials. Thecomputer-readable medium may comprise memory or data storage media, suchas random access memory (RAM) such as synchronous dynamic random accessmemory (SDRAM), read-only memory (ROM), non-volatile random accessmemory (NVRAM), electrically erasable programmable read-only memory(EEPROM), FLASH memory, magnetic or optical data storage media, and thelike. The techniques additionally, or alternatively, may be realized atleast in part by a computer-readable communication medium that carriesor communicates program code in the form of instructions or datastructures and that can be accessed, read, and/or executed by acomputer, such as propagated signals or waves.

The program code may be executed by a processor, which may include oneor more processors, such as one or more digital signal processors(DSPs), general purpose microprocessors, an application specificintegrated circuits (ASICs), field programmable logic arrays (FPGAs), orother equivalent integrated or discrete logic circuitry. Such aprocessor may be configured to perform any of the techniques describedin this disclosure. A general purpose processor may be a microprocessor;but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. Accordingly, the term “processor,” as used herein mayrefer to any of the foregoing structure, any combination of theforegoing structure, or any other structure or apparatus suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated software modules or hardware modules configured for encodingand decoding, or incorporated in a combined video encoder-decoder(CODEC).

Illustrative examples of the disclosure include:

Example 1

A method of processing video data. The method includes: obtaining acurrent block of a picture of the video data; determining the currentblock includes more than one virtual pipeline data unit (VPDU);obtaining, for illumination compensation, current neighbor samples forthe current block, the current neighbor samples including samples fromone or more of a first row of samples from a first neighboring block ofa first VPDU included in the current block or a first column of samplesfrom a second neighboring block of the first VPDU; obtaining, forillumination compensation, reference neighbor samples for the currentblock, the reference neighbor samples including samples from one or moreof a first row of samples from a first neighboring block of a referenceblock or a first column of samples from a second neighboring block ofthe reference block; obtaining, for illumination compensation,additional neighbor samples for the current block, the additionalneighbor samples including samples from one or more of a second row ofsamples from the first neighboring block of the first VPDU, a secondcolumn of samples from the second neighboring block of the first VPDU, asecond row of samples from the first neighboring block of the referenceblock, a second column of samples from the second neighboring block ofthe reference block, or samples from a neighboring block of a secondVPDU included in the current block; determining one or more illuminationcompensation parameters for the current block using the current neighborsamples, the reference neighbor samples, and the additional neighborsamples, the additional neighbor samples being used for determining theone or more illumination compensation parameters based on the currentblock covering more than one VPDU; and performing illuminationcompensation for the current block of the picture using the one or moreillumination compensation parameters.

Example 2

A method according to Example 1, further comprising: determining a sizeof a VPDU; determining one or more of a width or a height of the currentblock; determining one or more of the width or the height of the currentblock is larger than the size of the VPDU; and determining the currentblock includes more than one VPDU based on determining one or more ofthe width or the height of the current block is larger than the size ofthe VPDU.

Example 3

A method according to any of Examples 1 or 2, wherein the firstneighboring block of the first VPDU includes a top neighboring block,the second neighboring block of the first VPDU includes a leftneighboring block, the first neighboring block of the reference blockincludes a top neighboring block, and the second neighboring block ofthe reference block includes a left neighboring block.

Example 4

A method according to any of Examples 1 to 3, wherein subsampling is notapplied to samples from the first neighboring block of the first VPDU,samples from the second neighboring block of the first VPDU, samplesfrom the first neighboring block of the reference block, and samplesfrom the second neighboring block of the reference block when performingillumination compensation for the current block.

Example 5

A method according to any of Examples 1 to 4, wherein the additionalneighbor samples include samples from the second row of samples from thefirst neighboring block of the first VPDU and samples from the secondcolumn of samples from the second neighboring block of the first VPDU.

Example 6

A method according to Example 5, wherein the second row of samples fromthe first neighboring block of the first VPDU includes at least two rowsof samples, and wherein the second column of samples from the secondneighboring block of the first VPDU includes at least two columns ofsamples.

Example 7

A method according to any of Examples 1 to 6, wherein the additionalneighbor samples include samples from the second row of samples from thefirst neighboring block of the first VPDU, samples from second column ofsamples from the second neighboring block of the first VPDU, samplesfrom the second row of samples from the first neighboring block of thereference block, and samples from the second column of samples from thesecond neighboring block of the reference block.

Example 8

A method according to Example 7, wherein the second row of samples fromthe first neighboring block of the first VPDU includes at least two rowsof samples, wherein the second column of samples from the secondneighboring block of the first VPDU includes at least two columns ofsamples, wherein the second row of samples from the first neighboringblock of the reference block includes at least two rows of samples, andwherein the second column of samples from the second neighboring blockof the reference block includes at least two columns of samples.

Example 9

A method according to any of Examples 1 to 8, wherein the additionalneighbor samples include the samples from the neighboring block of thesecond VPDU included in the current block.

Example 10

A method according to any of Example 9, wherein the additional neighborsamples include samples from a neighboring block of a third VPDUincluded in the current block.

Example 11

A method according to Example 9, wherein the samples from theneighboring block of the second VPDU include a row of samples from theneighboring block of the second VPDU, and wherein the samples from theneighboring block of the third VPDU include a column of samples from theneighboring block of the third VPDU.

Example 12

A method according to Example 11, wherein the row of samples from thefirst neighboring block of the second VPDU includes at least two rows ofsamples, and wherein the column of samples from the neighboring block ofthe third VPDU includes at least two columns of samples.

Example 13

A method according to any of Examples 1 to 12, wherein the additionalneighbor samples include the samples from the neighboring block of thesecond VPDU, samples from the second row of samples from the firstneighboring block of the reference block, and samples from the secondcolumn of samples from the second neighboring block of the referenceblock.

Example 14

A method according to Example 13, wherein the samples from theneighboring block of the second VPDU include a row of samples from theneighboring block of the second VPDU and a column of samples from aneighboring block of a third VPDU.

Example 15

A method according to any of Examples 1 to 14, wherein the additionalneighbor samples include one or more of samples to a right of a topneighboring row of the current block, samples below a left neighboringcolumn of the current block, samples to a right of a top neighboring rowof the reference block, or samples below a left neighboring column ofthe reference block.

Example 16

A method according to any of Examples 1 to 15, wherein determining theone or more illumination compensation parameters for the current blockincludes minimizing a difference between one or more of the samples fromthe first row of samples from the first neighboring block of the firstVPDU or the samples from the first column of samples from the secondneighboring block of the first VPDU and one or more of the samples fromthe first row of samples from the first neighboring block of thereference block or the samples from the first column of samples from thesecond neighboring block of the reference block.

Example 17

A method according to any of Examples 1 to 16, wherein the one or moreillumination compensation parameters include at least one scaling factorand at least one offset.

Example 18

A method according to any of Examples 1 to 17, further comprisingdecoding the current block of video data based on performing theillumination compensation for the current block.

Example 19

A method according to any of Examples 1 to 18, further comprising:determining a residual value for the current block; performing aprediction mode for the current block; and reconstructing at least onesample of the current block based on the illumination compensationperformed for the current block, the residual value for the currentblock, and the prediction mode performed for the current block.

Example 20

A method according to any of Examples 1 to 19, further comprisinggenerating an encoded video bitstream, the encoded video bitstreamincluding at least a portion of the current block of video data.

Example 21

A method according to Example 20, further comprising signaling theencoded video bitstream.

Example 22

A method according to Example 20, further comprising signaling the oneor more illumination compensation parameters in the encoded videobitstream.

Example 23

An apparatus for processing video data according to any of Examples 1 to22. For example, the apparatus can include at least one memory and oneor more processors implemented in circuitry. The one or more processorsare configured to: obtain a current block of a picture of the videodata; determine the current block includes more than one virtualpipeline data unit (VPDU); obtain, for illumination compensation,current neighbor samples for the current block, the current neighborsamples including samples from one or more of a first row of samplesfrom a first neighboring block of a first VPDU included in the currentblock or a first column of samples from a second neighboring block ofthe first VPDU; obtain, for illumination compensation, referenceneighbor samples for the current block, the reference neighbor samplesincluding samples from one or more of a first row of samples from afirst neighboring block of a reference block or a first column ofsamples from a second neighboring block of the reference block; obtain,for illumination compensation, additional neighbor samples for thecurrent block, the additional neighbor samples including samples fromone or more of a second row of samples from the first neighboring blockof the first VPDU, a second column of samples from the secondneighboring block of the first VPDU, a second row of samples from thefirst neighboring block of the reference block, a second column ofsamples from the second neighboring block of the reference block, orsamples from a neighboring block of a second VPDU included in thecurrent block; determine one or more illumination compensationparameters for the current block using the current neighbor samples, thereference neighbor samples, and the additional neighbor samples, theadditional neighbor samples being used for determining the one or moreillumination compensation parameters based on the current block coveringmore than one VPDU; and perform illumination compensation for thecurrent block of the picture using the one or more illuminationcompensation parameters.

Example 24

An apparatus according to Example 23, wherein the apparatus comprises amobile device with a camera for capturing one or more pictures.

Example 25

An apparatus according to any of Examples 23 to 24, further comprising adisplay for displaying one or more pictures.

Example 26

A computer readable medium having stored thereon instructions that whenexecuted by a processor perform the methods of any of examples 1 to 22.

Example 27

An apparatus for processing video data, the apparatus includes means forperforming any of the operations of the methods of any of examples 1 to22.

Example 28

A method of processing video data, the method comprising: obtaining ablock of the video data; determining the block covers more than onevirtual pipeline data unit (VPDU); determining not to apply illuminationcompensation to the block based on the block covering more than oneVPDU; and processing the block of the video data.

Example 29

A method according to Example 28, wherein determining the block coversmore than one VPDU includes: determining the size of a VPDU; determiningone or more of a width or a height of the block; and determining one ormore of the width or the height of the block is larger than the size ofthe VPDU.

Example 30

A method according to any of Examples 28 to 29, further comprisingdetermining not to signal an illumination compensation flag for theblock in response to determining not to apply illumination compensationto the block, wherein an illumination compensation flag indicateswhether illumination compensation applies for a block.

Example 31

A method according to any of Examples 28 to 30, wherein determining notto apply illumination compensation to the block includes disablingillumination compensation for the block based on determiningbi-prediction is not used for the block.

Example 32

A method according to any of Examples 28 to 31, further comprising:obtaining an additional block of the video data; and performingillumincation compensation for the additional block, wherein performingthe illumination compensation includes: deriving one or moreillumination compensation parameters for the additional block; andapplying the one or more illumination compensation parameters to theadditional block.

Example 33

A method according to Example 32, wherein the one or more illuminationcompensation parameters for the additional block are derived usingneighboring reconstructed samples.

Example 34

A method according to Example 33, wherein the neighboring reconstructedsamples are from one or more of a first neighboring block of theadditional block and a second neighboring block of a reference blockused for inter-prediction.

Example 35

A method according to Example 34, wherein the first neighboring blockincludes one or more of a top neighboring block or a left neighboringblock of the additional block, and wherein the second neighboring blockincludes one or more of a top neighboring block or a left neighboringblock of the reference block.

Example 36

A method according to any of Examples 34 to 35, wherein deriving the oneor more illumination compensation parameters for the additional blockincludes minimizing a difference between reconstructed samples of thefirst neighboring block and reconstructed samples of the secondneighboring block.

Example 37

A method according to any of Examples 32 to 36, wherein the one or moreillumination compensation parameters include at least one scaling factorand at least one offset.

Example 38

A method according to any of Examples 32 to 37, wherein performing theillumination compensation on the additional block results in anillumination compensated predictor, and further comprising decoding theadditional block using the illumination compensated predictor.

Example 39

A method according to any of Examples 32 to 38, further comprisingsignaling the one or more illumination compensation parameters in anencoded video bitstream.

Example 40

A method according to any of Examples 28 to 39, wherein processing theblock of the video data includes decoding the block of video data.

Example 41

A method according to any of Examples 28 to 40, wherein processing theblock of the video data includes generating an encoded video bitstream,the encoded video bitstream including the block of video data.

Example 42

A method according to Example 41, further comprising signaling theencoded video bitstream.

Example 43

An apparatus comprising a memory configured to store video data and aprocessor configured to process the video data according to any ofexamples 28 to 42.

Example 44

An apparatus according to Example 43, wherein the apparatus includes adecoder.

Example 45

An apparatus according to any of Examples 43 to 44, wherein theapparatus includes an encoder.

Example 46

An apparatus according to any of Examples 43 to 45, wherein theapparatus is a mobile device.

Example 47

An apparatus according to any of Examples 43 to 46, wherein theapparatus includes a display configured to display the video data.

Example 48

An apparatus according to any of Examples 43 to 47, wherein theapparatus includes a camera configured to capture one or more pictures.

Example 49

A computer readable medium having stored thereon instructions that whenexecuted by a processor perform the methods of any of examples 28 to 42.

Example 50

A method of processing video data, the method comprising: obtaining ablock of the video data; determining the block covers more than onevirtual pipeline data unit (VPDU); performing illumincation compensationfor the block, wherein performing the illumincation compensationincludes deriving one or more illumination compensation parameters forthe block using samples from a first neighboring block of a current VPDUof the block and a second neighboring block of the current VPDU, a firstneighboring block of a reference block and a second neighboring block ofthe reference block, and additional samples, wherein the additionalsamples being used based on the block covering more than one VPDU; andprocessing the block of the video data.

Example 51

A method according to Example 50, wherein determining the block coversmore than one VPDU includes: determining the size of a VPDU; determiningone or more of a width or a height of the block; and determining one ormore of the width or the height of the block is larger than the size ofthe VPDU.

Example 52

A method according to any of Examples 50 to 51, wherein the firstneighboring block of the current block includes a top neighboring block,wherein the second neighboring block of the current block includes aleft neighboring block, wherein the first neighboring block of thereference block includes a top neighboring block, and wherein the secondneighboring block of the reference block includes a left neighboringblock.

Example 53

A method according to any of Examples 50 to 52, wherein down-sampling isnot applied to one or more of the samples of the first neighboring blockof the current block, the samples of the second neighboring block of thecurrent block, the samples of the first neighboring block of thereference block, and the samples of the second neighboring block of thereference block.

Example 54

A method according to any of Examples 50 to 53, wherein the additionalsamples include samples from one or more of an additional row of thefirst neighboring block of the current block, an additional column ofthe second neighboring block of the current block, an additional row ofthe first neighboring block of the reference block, and an additionalcolumn of the second neighboring block of the reference block.

Example 55

A method according to Example 54, wherein the additional samples includeat least two rows of the first neighboring block of the current block,at least two columns of the second neighboring block of the currentblock, at least two rows of the first neighboring block of the referenceblock, and at least two columns of the second neighboring block of thereference block.

Example 56

A method according to any of Examples 50 to 55, wherein the additionalsamples include neighboring samples from one or more other VPDUs of theblock.

Example 57

A method according to Example 56, wherein the additional samples furtherinclude samples from an additional row of the first neighboring block ofthe reference block and an additional column of the second neighboringblock of the reference block.

Example 58

A method according to Example 57, wherein the additional samples includeat least two rows of the first neighboring block of the reference blockand at least two columns of the second neighboring block of thereference block.

Example 59

A method according to any of Examples 50 to 58, wherein the additionalsamples include one or more of samples to a right of a top neighboringrow of the current block, samples below a left neighboring column of thecurrent block, samples to a right of a top neighboring row of thereference block, and samples below a left neighboring column of thereference block.

Example 60

A method according to any of Examples 50 to 59, further comprisingapplying the one or more illumination compensation parameters to theblock.

Example 61

A method according to any of Examples 50 to 60, wherein the one or moreillumination compensation parameters for the block are derived usingneighboring reconstructed samples.

Example 62

A method according to Example 61, wherein the neighboring reconstructedsamples are from one or more of a first neighboring block of the blockand a second neighboring block of a reference block used forinter-prediction.

Example 63

A method according to Example 62, wherein the first neighboring blockincludes one or more of a top neighboring block or a left neighboringblock of the block, and wherein the second neighboring block includesone or more of a top neighboring block or a left neighboring block ofthe reference block.

Example 64

A method according to any of Examples 62 to 63, wherein deriving the oneor more illumination compensation parameters for the block includesminimizing a difference between reconstructed samples of the firstneighboring block and reconstructed samples of the second neighboringblock.

Example 65

A method according to any of Examples 50 to 64, wherein the one or moreillumination compensation parameters include at least one scaling factorand at least one offset.

Example 66

A method according to any of Examples 50 to 65, wherein performing theillumination compensation on the block results in an illuminationcompensated predictor, and further comprising decoding the block usingthe illumination compensated predictor.

Example 67

A method according to any of Examples 50 to 66, further comprisingsignaling the one or more illumination compensation parameters in anencoded video bitstream.

Example 68

A method according to any of Examples 50 to 67, wherein processing theblock of the video data includes decoding the block of video data.

Example 69

A method according to any of Examples 50 to 68, wherein processing theblock of the video data includes generating an encoded video bitstream,the encoded video bitstream including the block of video data.

Example 70

A method according to Example 69, further comprising signaling theencoded video bitstream.

Example 71

An apparatus comprising a memory configured to store video data and aprocessor configured to process the video data according to any ofexamples 60 to 70.

Example 72

An apparatus according to Examples 71, wherein the apparatus includes adecoder.

Example 73

An apparatus according to any of Examples 71 to 72, wherein theapparatus includes an encoder.

Example 74

An apparatus according to any of Examples 71 to 73, wherein theapparatus is a mobile device.

Example 75

An apparatus according to any of Examples 71 to 74, wherein theapparatus includes a display configured to display the video data.

Example 76

An apparatus according to any of Examples 71 to 75, wherein theapparatus includes a camera configured to capture one or more pictures.

Example 77

A computer readable medium having stored thereon instructions that whenexecuted by a processor perform the methods of any of examples 50 to 70.

What is claimed is:
 1. A method of processing video data, the methodcomprising: obtaining a current block of a picture of the video data;determining the current block includes more than one virtual pipelinedata unit (VPDU); obtaining, for illumination compensation, currentneighbor samples for the current block, the current neighbor samplesincluding samples from one or more of a first row of samples from afirst neighboring block of a first VPDU included in the current block ora first column of samples from a second neighboring block of the firstVPDU; obtaining, for illumination compensation, reference neighborsamples for the current block, the reference neighbor samples includingsamples from one or more of a first row of samples from a firstneighboring block of a reference block or a first column of samples froma second neighboring block of the reference block; obtaining, forillumination compensation, additional neighbor samples for the currentblock, the additional neighbor samples including samples from one ormore of a second row of samples from the first neighboring block of thefirst VPDU, a second column of samples from the second neighboring blockof the first VPDU, a second row of samples from the first neighboringblock of the reference block, a second column of samples from the secondneighboring block of the reference block, or samples from a neighboringblock of a second VPDU included in the current block; determining one ormore illumination compensation parameters for the current block usingthe current neighbor samples, the reference neighbor samples, and theadditional neighbor samples, the additional neighbor samples being usedfor determining the one or more illumination compensation parametersbased on the current block covering more than one VPDU; and performingillumination compensation for the current block of the picture using theone or more illumination compensation parameters.
 2. The method of claim1, further comprising: determining a size of a VPDU; determining one ormore of a width or a height of the current block; determining one ormore of the width or the height of the current block is larger than thesize of the VPDU; and determining the current block includes more thanone VPDU based on determining one or more of the width or the height ofthe current block is larger than the size of the VPDU.
 3. The method ofclaim 1, wherein the first neighboring block of the first VPDU includesa top neighboring block, the second neighboring block of the first VPDUincludes a left neighboring block, the first neighboring block of thereference block includes a top neighboring block, and the secondneighboring block of the reference block includes a left neighboringblock.
 4. The method of claim 1, wherein subsampling is not applied tosamples from the first neighboring block of the first VPDU, samples fromthe second neighboring block of the first VPDU, samples from the firstneighboring block of the reference block, and samples from the secondneighboring block of the reference block when performing illuminationcompensation for the current block.
 5. The method of claim 1, whereinthe additional neighbor samples include samples from the second row ofsamples from the first neighboring block of the first VPDU and samplesfrom the second column of samples from the second neighboring block ofthe first VPDU.
 6. The method of claim 5, wherein the second row ofsamples from the first neighboring block of the first VPDU includes atleast two rows of samples, and wherein the second column of samples fromthe second neighboring block of the first VPDU includes at least twocolumns of samples.
 7. The method of claim 1, wherein the additionalneighbor samples include samples from the second row of samples from thefirst neighboring block of the first VPDU, samples from second column ofsamples from the second neighboring block of the first VPDU, samplesfrom the second row of samples from the first neighboring block of thereference block, and samples from the second column of samples from thesecond neighboring block of the reference block.
 8. The method of claim7, wherein the second row of samples from the first neighboring block ofthe first VPDU includes at least two rows of samples, wherein the secondcolumn of samples from the second neighboring block of the first VPDUincludes at least two columns of samples, wherein the second row ofsamples from the first neighboring block of the reference block includesat least two rows of samples, and wherein the second column of samplesfrom the second neighboring block of the reference block includes atleast two columns of samples.
 9. The method of claim 1, wherein theadditional neighbor samples include the samples from the neighboringblock of the second VPDU included in the current block.
 10. The methodof claim 9, wherein the additional neighbor samples include samples froma neighboring block of a third VPDU included in the current block. 11.The method of claim 9, wherein the samples from the neighboring block ofthe second VPDU include a row of samples from the neighboring block ofthe second VPDU, and wherein the samples from the neighboring block ofthe third VPDU include a column of samples from the neighboring block ofthe third VPDU.
 12. The method of claim 11, wherein the row of samplesfrom the first neighboring block of the second VPDU includes at leasttwo rows of samples, and wherein the column of samples from theneighboring block of the third VPDU includes at least two columns ofsamples.
 13. The method of claim 1, wherein the additional neighborsamples include the samples from the neighboring block of the secondVPDU, samples from the second row of samples from the first neighboringblock of the reference block, and samples from the second column ofsamples from the second neighboring block of the reference block. 14.The method of claim 13, wherein the samples from the neighboring blockof the second VPDU include a row of samples from the neighboring blockof the second VPDU and a column of samples from a neighboring block of athird VPDU.
 15. The method of claim 1, wherein the additional neighborsamples include one or more of samples to a right of a top neighboringrow of the current block, samples below a left neighboring column of thecurrent block, samples to a right of a top neighboring row of thereference block, or samples below a left neighboring column of thereference block.
 16. The method of claim 1, wherein determining the oneor more illumination compensation parameters for the current blockincludes minimizing a difference between one or more of the samples fromthe first row of samples from the first neighboring block of the firstVPDU or the samples from the first column of samples from the secondneighboring block of the first VPDU and one or more of the samples fromthe first row of samples from the first neighboring block of thereference block or the samples from the first column of samples from thesecond neighboring block of the reference block.
 17. The method of claim1, wherein the one or more illumination compensation parameters includeat least one scaling factor and at least one offset.
 18. The method ofclaim 1, further comprising decoding the current block of video databased on performing the illumination compensation for the current block.19. The method of claim 1, further comprising: determining a residualvalue for the current block; performing a prediction mode for thecurrent block; and reconstructing at least one sample of the currentblock based on the illumination compensation performed for the currentblock, the residual value for the current block, and the prediction modeperformed for the current block.
 20. The method of claim 1, furthercomprising generating an encoded video bitstream, the encoded videobitstream including at least a portion of the current block of videodata.
 21. The method of claim 20, further comprising signaling theencoded video bitstream.
 22. The method of claim 20, further comprisingsignaling the one or more illumination compensation parameters in theencoded video bitstream.
 23. An apparatus for processing video data, theapparatus comprising: at least one memory; and one or more processorsimplemented in circuitry and configured to: obtain a current block of apicture of the video data; determine the current block includes morethan one virtual pipeline data unit (VPDU); obtain, for illuminationcompensation, current neighbor samples for the current block, thecurrent neighbor samples including samples from one or more of a firstrow of samples from a first neighboring block of a first VPDU includedin the current block or a first column of samples from a secondneighboring block of the first VPDU; obtain, for illuminationcompensation, reference neighbor samples for the current block, thereference neighbor samples including samples from one or more of a firstrow of samples from a first neighboring block of a reference block or afirst column of samples from a second neighboring block of the referenceblock; obtain, for illumination compensation, additional neighborsamples for the current block, the additional neighbor samples includingsamples from one or more of a second row of samples from the firstneighboring block of the first VPDU, a second column of samples from thesecond neighboring block of the first VPDU, a second row of samples fromthe first neighboring block of the reference block, a second column ofsamples from the second neighboring block of the reference block, orsamples from a neighboring block of a second VPDU included in thecurrent block; determine one or more illumination compensationparameters for the current block using the current neighbor samples, thereference neighbor samples, and the additional neighbor samples, theadditional neighbor samples being used for determining the one or moreillumination compensation parameters based on the current block coveringmore than one VPDU; and perform illumination compensation for thecurrent block of the picture using the one or more illuminationcompensation parameters.
 24. The apparatus of claim 23, furthercomprising: determining a size of a VPDU; determining one or more of awidth or a height of the current block; determining one or more of thewidth or the height of the current block is larger than the size of theVPDU; and determining the current block includes more than one VPDUbased on determining one or more of the width or the height of thecurrent block is larger than the size of the VPDU.
 25. The apparatus ofclaim 23, wherein the first neighboring block of the first VPDU includesa top neighboring block, the second neighboring block of the first VPDUincludes a left neighboring block, the first neighboring block of thereference block includes a top neighboring block, and the secondneighboring block of the reference block includes a left neighboringblock.
 26. The apparatus of claim 23, wherein the additional neighborsamples include samples from the second row of samples from the firstneighboring block of the first VPDU and samples from the second columnof samples from the second neighboring block of the first VPDU.
 27. Theapparatus of claim 23, wherein the additional neighbor samples includesamples from the second row of samples from the first neighboring blockof the first VPDU, samples from second column of samples from the secondneighboring block of the first VPDU, samples from the second row ofsamples from the first neighboring block of the reference block, andsamples from the second column of samples from the second neighboringblock of the reference block.
 28. The apparatus of claim 23, wherein theapparatus comprises a mobile device with a camera for capturing one ormore pictures.
 29. The apparatus of claim 23, further comprising adisplay for displaying one or more pictures.
 30. A non-transitorycomputer-readable medium having stored thereon instructions that, whenexecuted by one or more processors, cause the one or more processors to:obtain a current block of a picture of the video data; determine thecurrent block includes more than one virtual pipeline data unit (VPDU);obtain, for illumination compensation, current neighbor samples for thecurrent block, the current neighbor samples including samples from oneor more of a first row of samples from a first neighboring block of afirst VPDU included in the current block or a first column of samplesfrom a second neighboring block of the first VPDU; obtain, forillumination compensation, reference neighbor samples for the currentblock, the reference neighbor samples including samples from one or moreof a first row of samples from a first neighboring block of a referenceblock or a first column of samples from a second neighboring block ofthe reference block; obtain, for illumination compensation, additionalneighbor samples for the current block, the additional neighbor samplesincluding samples from one or more of a second row of samples from thefirst neighboring block of the first VPDU, a second column of samplesfrom the second neighboring block of the first VPDU, a second row ofsamples from the first neighboring block of the reference block, asecond column of samples from the second neighboring block of thereference block, or samples from a neighboring block of a second VPDUincluded in the current block; determine one or more illuminationcompensation parameters for the current block using the current neighborsamples, the reference neighbor samples, and the additional neighborsamples, the additional neighbor samples being used for determining theone or more illumination compensation parameters based on the currentblock covering more than one VPDU; and perform illumination compensationfor the current block of the picture using the one or more illuminationcompensation parameters.